Okay, first of all, this will probably be the shortest entry I do. Mostly because when I was doing my pre-entry research, I came up with exactly nothing in the way of internet material. The only bits I have are Cosplay Station Zero’s short comments on self casting, found here.
The second bit is word of mouth advice I gathered, which I’m going play for you below. In this short podcast are people from Costume Station Zero, and from personal acquaintance, who have a lot of experience between them.
Mostly, it boils down to this: You can choose a character that you look just like, if you want something easy.
However, cosplay isn’t done because it is easy. It’s done because you love it. So fly your colors, even if those colors require a wig and lots of makeup!