You could always opt for laser surgery. There's a procedure out there that gets rid of stretch marks. It's costly, but if they really bother you that much save up and get it done.
There are also creams that can be bought in the store for them, but IMO, they are a waste of money and don't work.
A cheap alternative is to buy a cocoa butter stick and use it everyday on them. That's been used for a long time. You'll just smell like cocoa butter.
The best thing you can do is stay moisturized. About 3 times a day use a good lotion on the areas your concerned with.* Remember: your body is growing and therefore your skin is going to stretch, the more consistant you are with applying the lotion (after showers, prior to work-outs, times that make the most sense, etc).
Hope this helps.