Well... I've never had one. I think though... rather than just getting what you want, if you want to look 'good' to others you'll want to instead find out what fits more accordingly with your face. A tiny nose in a big face (especially when this surgery is meant to make you look better) is just plain ugly. Like... Michael Jackson (may he rest in peace), his nose surgeries were just... disfiguring rather than making him look better.
However, it may be that you absolutely want it smaller regardless of what others think, then by all means.
Sometimes trauma makes us want to change something about ourselves. Remember though that you'll need a lot of counseling before and after the procedure.
Have you ever heard of Body Dysmorphic Disorder?
http://en.wikipedia.org/wiki/Body_dysmorphic_disorder
You may THINK your nose is too big... but others see it as normal. It IS normal... because being different IS normal. You have to either accept it, or change it... but sometimes even when you change things... you're not happy. Think a lot about these things before you go under the knife. The damages may be worse than the good that comes out of it.