Like others have said just use what you have to practice and get a feel for it. I started off with an Aztek and it is IMHO garbage. Bought an Iwata Ecplise a few months later and never looked back. I picked up a Harder and Steenbeck Infinity along the way but only used it twice. It's a very nice 'brush but the Iwata does it all for me. Here's my most complicated paint job to date. All the gradations were sprayed by hand.
http://imageshack.com/a/img171/1192/img2556t.jpg
http://imageshack.com/a/img84/9902/img2546cc.jpg
http://imageshack.com/a/img690/479/img2537r.jpg
http://imageshack.com/a/img36/4121/img2539si.jpg