No one is born a makeup artist, and makeup, like anything else, takes practice. My suggestion for you is simply to begin experimenting more often. You don't even have to wear it out of the house, in fact, I usually reserve trying new looks for a lonely Saturday so if it looks bad no one but me has to see. You may also want to check out beauty tutorials on Youtube, I'm a big fan of Michelle Phan, as well as Meghan Rosette, and there are plenty of other beauty gurus to check out. Also start small and work your way up, you have to be able to do the basics before you can master more intricate designs.
Hope this helps and good luck!