I don't cosplay myself, nor do I know anyone that does. I agree with Lekana, that for the most part, the costumes never look right, nor do the people wearing them.

Having said that, I was surfing just today and found this website, it was linked from a FFVIII site that had a bunch of stuff on it including some cosplay photos.

I think this girl is the exception to cosplay not the rule. Her costumes are spot on.

http://adellacosplay.com/

Here's her Aeris costume:

http://www.adellacosplay.com/cosplay/gallery/C2/aeris/