ORIGINAL: TheBum
There's one other consideration: available flying space. You can fly a mini in a smaller area than a Nitro 50/Electric 600. I could have never gone through my early learning stages in my backyard with anything larger than a mini.
Common mistake that newibes make. DO NOT TRY TO LEARN BY YOURSELF. It will take double the time and effort if you try it by yourself. An experienced flying buddy will make the learning curve shallower and simpler.
I still recommend 50 sized nitros or 600 sized electrics if the funds are avaialble. They are the best the money can buy right now. Minis are good, but once you try a 50 or 600 sized heli you will ask yourself, what was I thinking?!
Rafael