TikZ, in common with Beamer and Memoir, is a very, very rich, and, as a result, intimidating, package, so don't feel too bad about it.
The way I learned all three was basically demand-driven --- "learning by doing". Whenever I needed something "new", I'd dig into the manual and try stuff until either it worked (not always most elegantly), or in desperation go to the examples website, or moan here on TeX-'n-Friends. Occasionally supplemented by trying to answer "challenging" questions here.
After what --- one or two years --- that additional effort has worked like a savings account, and I now have the three tools on my belt, with which I can do almost everything I need. I still need to go back to the manuals, but it's a lot easier now.