gregory said:
What deck are you using ? Makes a lot of difference !
One book that I absolutely adore - though it will help more with RWS-like decks than with the Thoth variants - is Mark McElroy` s Absolute Beginner`s Guide to Tarot (ISBN 0-7897-3515-6).
I discovered it pretty late but so it is easier for me to rate and value it highly. One of the very good things about it is that every card is presented as it looks in four different decks (something like the idea of comparative tarot - working out the essentials by comparing different interpretations), that card interpretations are logically and usefully structured and that the style of writing is very agreeable and no-nonsense.
Get a copy of Sandra Thomson´s Pictures from the Heart (ISBN 0312-29128-0) to accompany it, a tarot "dictionary" which is very easily accessible and profound at the same time (and uses the same comparative, multi-deck approach as the former book) - and in my view you are set for a very long time.
You might eventually add Mary Greer´s The Complete Book of Tarot Reversals (ISBN 978-1-56718-285-9) after a while.
Never mind, there are many good tarot books and you will certainly receive a lot of additional - and different - recommendations.
Good luck!