Photoshop
I've wanted to do the same thing. But first, you should pick out what celebrity you would want them to be like. Take Angela Genovese, for instance. She wears skinny jeans, so choose the pants that are darkest for your sim. Make it have long hair, and do the same with the shirt. Add accesories if you want to. If you want it to look like you, try
Photoshop and save the picture to Sim Creater.
