Most Helpful Girl
Big as in overweight? Or big as in tall?
Mostly, just be yourself and wear what is comfortable for you. If you wear something specifically to look more 'attractive' (which is a relative term, really) but aren't comfortable in it, that's going to show and it's going to make you look less attractive than any physical (I'm assuming that you mean overweight, since that is usually what people use the word 'big' for) 'flaw'.