Teeth problems

I'm now nearly 18 and my teeth are quite badly discoloured. Depending on the light source, they range from acceptable, but not great, to pretty horrible. It doesn't help that one of my front teeth has a small chip on it from when I was very young (off my primary teeth), which is very white so it really shows how bad the rest are. I've cut out coffee completely from my intake and drink one cup of tea a day and maybe a can of coke twice a week. I don't smoke and I clean my teeth well at least twice a day.

I did wear braces when I was younger and I think that's when it got a lot worse, though I can't ever remember having a very white smile.

Obviously the dentist is going to be the first port of call on this one, but if anyone has any advice or experiences that would be tres helpful... thanks.