Cosplayers I need your help?

I've never actually cosplayed, but my brother's girlfriend does it quite a bit. She does a sketch first of the clothing she is going to wear. So sketching clothing would probably be the first step in order to know what dimensions you need for cloth. Know what colors you need, etc etc. Then when that happens, buy the cloth, sow, stitch, do whatever you have to do to get the sketch completed, and then do your hair, etc etc. I'm not too sure how much it costs, but I know it's not that cheap.