Newsround went to meet Paula Karaiskos from top model agency Storm, who discovered stars like Kate Moss and Lily Cole.
Most of the models Storm sign up are adults, but they take on a few under 16s and say they look at every photo that kids send in.
Storm's top tips for modelling
1. You don't need to spend money on expensive photos. Holiday snaps or pictures of you at home are much better because you look more natural.
2. Don't wear loads of make-up in your pictures
3. Be careful replying to adverts for models. Phone the company and find out more about them. Proper agencies will ask you to meet them in an office, not a hotel or café.
4. If you are stopped on the street, never go off with a stranger - even if they are promising to make you famous! Arrange another time to meet them with a parent or guardian.
5. It might be worth waiting until you are 14 before you approach an agency, because your looks change a lot as you are growing up.