Hi Shikhs,
one of the best ways to approach the Crowley's Thoth deck is to read to the correspondence between him and the artist of the deck, Frieda Harris.
(two sites with the letters concerning the Thoth deck)
http://www.hermetic.com/crowley/crowley-harris.html
http://www.geocities.com/Athens/Acropolis/1896/crowhar.html
It is deep stuff, but it is a beginning and for Crowley studies, the only way is to jump in head first, in the deep end. I can't recommend starter books like - can't remember his name - because I haven't read them.
The Thoth deck is one of the most beautiful tarot creations ever. My advice -
1. Buy the deck (any version I guess)
2. Buy "The Book of Thoth" and study it. Follow up with the bibliography - mostly other Crowley books.
3. Study the Crowley-Harris letters.
4. Get "Magick Without Tears", which is another series of letters by Crowley, at the same time the deck was being created.
5. Learn something about the Steiner "projective" geometry Harris used to create the cards. I think some people have recommended sites in this thread before.
I hope you find the Thoth deck as deep and powerful as I have in my 27 years of study of it.
Ross