Ariel,
I have four different books on braiding:
Encyclopedia of Rawhide and Leather Braiding - Bruce Grant
How to Make Cowboy Horse Gear - Bruce Grant
Braiding Rawhide Horse Tack - Robert L. Wooley
Braiding Fine Leather - David W. Morgan
I'm just learning how to braid myself and when I attempt to braid something I usually pick up Encyclopedia of Rawhide and Leather Braiding. Although I fully agree with Myriam that some of the illustrations can be misleading. I've only seen some of Gail Hought's braiding instructions on the internet and did find them a lot easier to follow. From what I've seen her books are expensive, but I've read they are well worth it. I've also heard that some of her more advanced books refer back to some of her other books to tie certain knots, etc.
How to Make Cowboy Horse Gear is a condensed version of Encyclopedia of Rawhide and Leather Braiding with a section about saddles.
Braiding Rawhide Horse Tack is very hard to understand, so I don't even open it up.
Braiding Fine Leather has sections for round braiding, flat braiding and then sections on how to make projects such as a Key Lanyard, Whistle Lanyard, Dog Leash, Hatband and Belt. Again not one of my favorite.
My personal pick is the Encyclopedia of Rawhide and Leather Braiding and I still have plans on buying The Art of Braiding, Basics - Revised Edition by Gail Hought as Mariam mentioned.
Good luck,
Butch