Don't give up. In six months you'll be awed with how much you know about Tarot, and will be tempted to brag to everyone about your awesome skills and Otherworldly contacts. In five years, you'll be starting to notice that there are things you don't know. In twenty years or so, you'll be feeling like a beginner, learning thirstily every day. So you'll be learning for the rest of your life. Don't give up - it's worth it.
Oh, and never, EVER, presume that you know what's best for your clients more than they do.
So that's really two pieces of advice, but they're both crucial.