Tic Tac Toe

Why can't I ever win at this game??? Every time I play with my friends, I usually lose and occasionally tie. When I play with the computer, I almost ALWAYS lose. :( I don't know how some people can win so easily. It's like there's this strategy to the game. Some secret way to win at this game... That no one has bothered to tell me about. It's kinda like the Rubik's Cube (I think i spelt that wrong). I have this friend who is sooo amazingly good at it. She has this formula for the 3x3 one, the 2x2, the 4x4, and the void cube. The void cube is soooo cool. The middle is missing on all sides and tops. Ooooh, fancy. I can't even solve the easiest 3x3 so I had no chance at the void cube. I tried, I failed. I tried again, I succeeded. Only because I only turned the sides once when I was mixing it. :) With the void cube, all I really do is poke my fingers through the holes and watch my friend solve it. It's actaully really amusing just watching pros solve it. They spin the sides so quickly. :)