you can try to do street photography, but you'll more likely end up doing general portrait work. the photography market for portraits is open and fairly easy to get into, but as soon as you venture into the more creative realms, you're looking at a select few who get to do it professionally. nature, street, abstract, product, model, and even high-end wedding photography are really hard to get into. you have to prove yourself.
talk to some portrait photographers and find out if that's something you want to do. if so, go into it, and do the other as a hobby, building yourself a portfolio. study hard, and keep your mind open. you have to learn how to use the art rules, bend and even break them to get attention and be pro in the creative fields.
get yourself a copy of photoshop cs4 or 5, and learn how to use it for unique effects. learn to use photoshop light room to speed up work flow.
finally have a back-up plan, because, as is the case with all art trades, work can fluctuate greatly, and you can't rely on it as your sole source of income, until you are firmly established.