Great question...
When I started with my first deck, I read the book that accompanied and "learned the meanings" for the cards. Then I found AT, and when I began to read others' interpretations of the cards, it really shook me. I was so confused. Why were books and booklets available with the decks if the right thing to do was to wing it intuitively? Why, in the readings threads, did so many people seem to have conflicting opinions about cards and what they meant in a particular reading? How could anyone expect that a reading could be "true" if another reader, given the same cards in the same spread, could come up with a totally different reading?
So I basically put all I had learned from my books on a back shelf somewhere in my mind, keeping that knowledge for reference, but not accepting it as gospel. Then I spent hours on AT soaking up conversation, study, debate, and opinion. I also began giving my deck a good workout, using it constantly by doing readings for everything I could think of, comparisons, meditation, and just plain admiration.
Basically, that's still where I'm at. My confidence in my readings has grown by leaps and bounds. I read all the tarot books I can find and also just kind of go with what comes to mind in a reading. I'm still watching the threads, inspired by and sometimes in awe of the members here who sit so far above me in their skill, but the combination of it all has me feeling stronger and more sure of myself daily.
Just my own experience, but I thought I'd share. Good luck to you.