No Lord of the Rings costume list would be complete without mentioning AlleyCatScratch and the Costumer's Guide. They are the prime sites for resources and information for every LotR costume you can think of!
Screencaps and reference pictures are linked to their respective sources, though many screencaps are from Movie-Screencaps.com.
I'll be updating as I find tutorials, and please feel free to leave suggestions in the comments!
Elves:
Arwen
Galadriel
Tauriel
Human:
Eowyn
Hobbit:
Rosie Cotton
Elves:
Arwen:
Chase Dress (Fellowship of the Ring):
Alleycatscratch Research Page for Arwen's Chase Dress
Costumer's Guide Research Page for Arwen's Chase Dress
Costumer's Guide Research Page for Arwen's Chase Dress
Arwen's Chase Dress by Bright Copper Penny
Arwen's Chase Dress by Kelldar
Arwen's Chase Dress by GothicFaerie87
Arwen's Chase Dress by Maggie from Costumer's Guide
Arwen's Chase Dress by Maris
Arwen's Chase Dress Mock-Up by Elana
Arwen's Chase Dress by Kayla
Arwen's Chase Dress by Rachel
Arwen's Chase Dress by Nulomiel
Bridge Dress (Fellowship of the Ring):
AlleyCatScratch's Research Page for Arwen's Bridge Dress
Costumer's Guide Research Page for Arwen's Bridge Dress
Arwen's Bridge Dress by Very Faery
Arwen's Bridge Dress by Therese
Arwen's Bridge Dress by GothicFaerie87
Farewell Dress (Fellowship of the Ring Extended Edition):
AlleyCatScratch's Research Page for Arwen's Farewell Dress
Costumer's Guide Research Page for Arwen's Farewell Dress
Arwen's Farewell Dress by Very Faery
Arwen's Rivendell Farewell Dress by Trystan Craft
Arwen's Farewell Dress by Ashley
Arwen's Farewell Dress, Embroidery, Sleeves by Dintarmawen Design
Arwen's Farewell Dress by Elwynsweb
Arwen's Farewell Dress by Merenwen
Hope Dress (The Two Towers):
AlleyCatScratch's Research Page for Arwen's Hope Dress
Costumer's Guide Research Page for Arwen's Hope Dress
Arwen's Hope Dress by White Lady of Rohan
Arwen's Hope Dress Version by Elwynsweb
Mourning Dress (The Two Towers):
Arwen's Chase Dress by Kelldar
Arwen's Chase Dress by GothicFaerie87
Arwen's Chase Dress by Maggie from Costumer's Guide
Arwen's Chase Dress by Maris
Arwen's Chase Dress Mock-Up by Elana
Arwen's Chase Dress by Kayla
Arwen's Chase Dress by Rachel
Arwen's Chase Dress by Nulomiel
Bridge Dress (Fellowship of the Ring):
Costumer's Guide Research Page for Arwen's Bridge Dress
Arwen's Bridge Dress by Very Faery
Arwen's Bridge Dress by Therese
Arwen's Bridge Dress by GothicFaerie87
Farewell Dress (Fellowship of the Ring Extended Edition):
Costumer's Guide Research Page for Arwen's Farewell Dress
Arwen's Farewell Dress by Very Faery
Arwen's Rivendell Farewell Dress by Trystan Craft
Arwen's Farewell Dress by Ashley
Arwen's Farewell Dress, Embroidery, Sleeves by Dintarmawen Design
Arwen's Farewell Dress by Elwynsweb
Arwen's Farewell Dress by Merenwen
Dream Dress (The Two Towers):
Hope Dress (The Two Towers):
Costumer's Guide Research Page for Arwen's Hope Dress
Arwen's Hope Dress by White Lady of Rohan
Arwen's Hope Dress Version by Elwynsweb
Mourning Dress (The Two Towers):
Cranberry Dress (The Two Towers):
Requiem Dress (Return of the King):
AlleyCatScratch's Research Page for Arwen's Requiem Dress
AlleyCatScratch's Making of Page for Arwen's Requiem Dress
AlleyCatScratch's Making of Page for Arwen's Requiem Dress
Arwen's Requiem Dress by Very Faery
Arwen's Requiem Dress by Katie (page with close-up of embroidery)
Arwen's Requiem Dress by Aimee Major
Arwen's Requiem Dress by Jen from the Masquerade Lab
Arwen's Requiem Dress by Hannah
Arwen's Requiem Dress by Merenwen
Arwen's Requiem Dress by CostumeGurly
Arwen's Requiem Dress by Donna
Arwen's Requiem Dress and Cloak by Maggie
Arwen's Requiem Dress by Tammy
Arwen's Requiem Dress by AriaCouture
Arwen's Requiem Dress by Katie (page with close-up of embroidery)
Arwen's Requiem Dress by Aimee Major
Arwen's Requiem Dress by Jen from the Masquerade Lab
Arwen's Requiem Dress by Hannah
Arwen's Requiem Dress by Merenwen
Arwen's Requiem Dress by CostumeGurly
Arwen's Requiem Dress by Donna
Arwen's Requiem Dress and Cloak by Maggie
Arwen's Requiem Dress by Tammy
Arwen's Requiem Dress by AriaCouture
Blood Red Gown (Return of the King):
AlleyCatScratch's Research Page for Arwen's Blood Red Gown
AlleyCatScratch's Making of Page for Arwen's Blood Red Gown
AlleyCatScratch's Making of Page for Arwen's Blood Red Gown
Arwen's Blood Red Gown by Naira
Arwen's Blood Red Gown by Aria Couture
Arwen's Blood Red Gown by Hayley
Arwen's Blood Red Gown by Sidhe
Arwen's Blood Red Gown by Annie
Arwen's Blood Red Gown by Aria Couture
Arwen's Blood Red Gown by Hayley
Arwen's Blood Red Gown by Sidhe
Arwen's Blood Red Gown by Annie
Reforging Narsil Cloak and Gown (Return of the King):
Green Wedding/Coronation Gown (Return of the King):
Costumer's Guide Research Page for Arwen's Green Coronation Gown
Kay-Dee's Research Notes on Color and Construction of Green Coronation Gown
Arwen's Coronation Gown by Aletheia NocturneKay-Dee's Research Notes on Color and Construction of Green Coronation Gown
Arwen's Coronation Gown by Aimee Major
Arwen's Coronation Gown by Karolina
Arwen's Coronation Gown by Very Faery
Arwen's Coronation Gown by Ariel
Arwen's Coronation Gown by Simbelmyne
Arwen's Coronation Gown by Francesca
Arwen's Coronation Gown and Crown Construction by Michelle
Arwen's Coronation Gown by Aria Couture
Arwen's Coronation Gown Makeover by Lisha Vidler
Arwen's Coronation Gown by Sarah
Arwen's Coronation Gown by Heather
Rose Gown (Cut from Fellowship of the Ring):
Arch Dress (Cut from Fellowship of the Ring):
Costumer's Guide Research Page for Arwen's Arch Dress
Arwen's Arch Dress by Maggie from Costumer's Guide
Arwen's Arch Dress by Yvette
Arwen's Arch Dress by Esteria
Arwen's Arch Dress by Maggie from Costumer's Guide
Arwen's Arch Dress by Yvette
Arwen's Arch Dress by Esteria
Beaded Lavender Gown (Cut from Two Towers):
Arwen's Lavender Beaded Gown by Yvette (scroll down to see notes)
Arwen's Lavender Beaded Gown by Donna
Arwen's Lavender Beaded Gown by Donna
Battle Outfit (Cut from Two Towers):
Galadriel:
Prologue/ Grey Havens Dress (Fellowship of the Ring/ Return of the King):
Mirror Dress (Fellowship of the Ring):
Under a Spell/ Dark Queen Dress (Fellowship of the Ring):
White Council Dress (An Unexpected Journey):
Lace White Dress (Desolation of Smaug):
No write-ups as of yet
Tauriel:
Human:
Eowyn:
Green Gown (The Two Towers):
Costumer's Guide Research Page for Eowyn's Green Gown
Eowyn's Green Gown Construction Notes Part 1, Part 2, and Mantle by Yvette
Eowyn's Green Gown Diary by Simbelmyne
Eowyn's Green Gown Notes by Mohmoh
Inspired by Eowyn's Green Dress Diary by JennylaFleur
Eowyn's Green Dress by Cation Designs
Eowyn's Green Dress by Thornberry
Eowyn's Green Dress by Kristi
Eowyn's Green Gown Construction Notes by Jen from The Masquerade Lab
Eowyn's Green Gown by Sarah
Eowyn's Green Gown by Jutta
Eowyn's Green Gown Construction Notes Part 1, Part 2, and Mantle by Yvette
Eowyn's Green Gown Diary by Simbelmyne
Eowyn's Green Gown Notes by Mohmoh
Inspired by Eowyn's Green Dress Diary by JennylaFleur
Eowyn's Green Dress by Cation Designs
Eowyn's Green Dress by Thornberry
Eowyn's Green Dress by Kristi
Eowyn's Green Gown Construction Notes by Jen from The Masquerade Lab
Eowyn's Green Gown by Sarah
Eowyn's Green Gown by Jutta
White Wool Gown (The Two Towers):
Costumer's Guide Research Page for Eowyn's White Wool Gown
Eowyn's White Wool Gown Costume Notes by Kairi G Cosplay
Eowyn's White Wool Gown Construction by Koshka
Eowyn's White Wool Making Of Notes by Katie
Eowyn's White Wool Gown Notes by K. Furgerson
Eowyn's White Wool Gown by Shannon
Eowyn's White Wool Gown by Amy
Eowyn's White Wool Gown by Dendera
Eowyn's White Wool Gown by Amanda
Eowyn's White Wool Gown by mdb
Eowyn's White Wool Gown by Candice
Eowyn's White Wool Gown by Jude
Eowyn's While Wool Gown Construction Notes by Mia
Eowyn's White Wool Gown Costume Notes by Kairi G Cosplay
Eowyn's White Wool Gown Construction by Koshka
Eowyn's White Wool Making Of Notes by Katie
Eowyn's White Wool Gown Notes by K. Furgerson
Eowyn's White Wool Gown by Shannon
Eowyn's White Wool Gown by Amy
Eowyn's White Wool Gown by Dendera
Eowyn's White Wool Gown by Amanda
Eowyn's White Wool Gown by mdb
Eowyn's White Wool Gown by Candice
Eowyn's White Wool Gown by Jude
Eowyn's While Wool Gown Construction Notes by Mia
Funeral Gown (The Two Towers):
Costumer's Guide Research Page for Eowyn's Funeral Gown
Eowyn's Funeral Gown by CostumeKullan
Eowyn's Funeral Inspired Gown by Manwariel
Eowyn's Funeral Gown by Twin Roses Designs (scroll down)
Traveling Coat (The Two Towers):
Eowyn's Traveling Coat Construction Notes by Jen G.
Eowyn's Traveling Coat Construction Notes by Aya
Eowyn's Traveling Coat Construction Notes by SisterSola
Eowyn's Traveling Coat by Jessica
Eowyn's Traveling Coat by Sarah R.
Refugee Dress (The Two Towers):
Eowyn's Funeral Gown by CostumeKullan
Eowyn's Funeral Inspired Gown by Manwariel
Eowyn's Funeral Gown by Twin Roses Designs (scroll down)
Traveling Coat (The Two Towers):
Eowyn's Traveling Coat Construction Notes by Aya
Eowyn's Traveling Coat Construction Notes by SisterSola
Eowyn's Traveling Coat by Jessica
Eowyn's Traveling Coat by Sarah R.
Refugee Dress (The Two Towers):
Beacon Dress (The Return of the King):
Costumer's Guide Research Page for Eowyn's Beacon Dress
Eowyn's Beacon Dress Construction Notes by Mohmoh
Eowyn's Beacon Dress by Lady--Eowyn on Deviantart (No costume notes, but great detail)
Eowyn's Beacon Dress Construction Notes by Mohmoh
Eowyn's Beacon Dress by Lady--Eowyn on Deviantart (No costume notes, but great detail)
Victory Gown (The Return of the King):
Costumer's Guide Research Page for Eowyn's Victory Gown
Eowyn's Victory Gown Construction Notes by Mohmoh
Eowyn's Victory Gown Construction Notes by The Casual Costumer
Eowyn's Victory Gown Construction Notes by Weirde Sisters
Eowyn's Victory Gown by KR Swanson
Eowyn's Victory Gown by Haladin
Eowyn's Victory Gown Construction Notes by Mohmoh
Eowyn's Victory Gown Construction Notes by The Casual Costumer
Eowyn's Victory Gown Construction Notes by Weirde Sisters
Eowyn's Victory Gown by KR Swanson
Eowyn's Victory Gown by Haladin
Riding Costume (The Return of the King):
Costumer's Guide Research Page for Eowyn's Riding Costume
Eowyn's Riding Outfit by Lady--Eowyn on Deviantart (No costume notes, but great detail)
Eowyn's Riding Outfit by Lady--Eowyn on Deviantart (No costume notes, but great detail)
Shieldmaiden (The Return of the King):
Costumer's Guide Research Page for Eowyn's Shieldmaiden Costume
Éowyn's Shieldmaiden Dress Tutorial by HappilyGrim
Eowyn's Shieldmaiden Dress Costume Notes by Kelldar
Eowyn's Shieldmaiden Dress Tutorial by Koshka the Cat
Eowyn's Shieldmaiden Dress Tutorial by Maggie
Eowyn's Shieldmaiden Dress Construction Notes by Yvette
Eowyn's Shieldmaiden Dress Costume Notes by Caitlin
Eowyn's Shieldmaiden Dress Costume Notes by Aranel
Eowyn's Shieldmaiden Dress Costume Notes by Karina
Eowyn's Shieldmaiden Dress Costume Notes by Sewing Season
Eowyn's Shieldmaiden Dress Costume Notes by Becky
Eowyn's Shieldmaiden Dress Costume Notes by Carissa
Eowyn's Shieldmaiden Dress Costume Notes by Annie
Éowyn's Shieldmaiden Dress Tutorial by HappilyGrim
Eowyn's Shieldmaiden Dress Costume Notes by Kelldar
Eowyn's Shieldmaiden Dress Tutorial by Koshka the Cat
Eowyn's Shieldmaiden Dress Tutorial by Maggie
Eowyn's Shieldmaiden Dress Construction Notes by Yvette
Eowyn's Shieldmaiden Dress Costume Notes by Caitlin
Eowyn's Shieldmaiden Dress Costume Notes by Aranel
Eowyn's Shieldmaiden Dress Costume Notes by Karina
Eowyn's Shieldmaiden Dress Costume Notes by Sewing Season
Eowyn's Shieldmaiden Dress Costume Notes by Becky
Eowyn's Shieldmaiden Dress Costume Notes by Carissa
Eowyn's Shieldmaiden Dress Costume Notes by Annie
Dernhelm
Costumer's Guide Research Page for Eowyn's Dernhelm Costume
Eowyn's Dernhelm Armor Walkthrough by Garfeimao (Amazing details!)
Eowyn's Dernhelm Armor Costume Notes by Lina (In German, but lots of progress pictures)
Eowyn's Dernhelm Armor by Lady--Eowyn (No costume notes, but great detail)
Eowyn's Dernhelm Armor Walkthrough by Garfeimao (Amazing details!)
Eowyn's Dernhelm Armor Costume Notes by Lina (In German, but lots of progress pictures)
Eowyn's Dernhelm Armor by Lady--Eowyn (No costume notes, but great detail)
Starry Mantle
Coronation
Hobbit:
Rosie Cotton:
Thanks for reading, and if you have a tutorial you'd like to add, let me know in the comments!