Ok this depends entirely on your budget, people suggest bio oil and cocoa butter which is a great and cheap way to help reduce stretch marks and since your only 24, it will be more effective.
BUUUT, my aunt has recently purchased (for a cool £10,000!) a machine for INABE(?) treatments which really do reduce cellulite, jowels, puffy eyes, stretchmarks and scars etc. It really does work and she already has a cliental of some particularly famous people as a result
The machine itself looks like a computer from the 70's haha. Unfortunately courses run into the 100's mark and for it to have an effect you WILL have to have around a course of 20 maybe more.
If you have the cash or desperately want to get rid of them, this is the best way and maybe you should search around for anyone who does this?
Also, for cellulite, when your in the shower, try using a scrubbing brush to massage your problem areas, that should help the lymphatic drainage.
I recently got a cigarrette burn on my arm (nice) and Ive been using bio oil on the morning and evening for almost 3 months now, I cant tell if its really improved but it does seem like its fading faster.