Rubik's Cube

This has been taking quite a bit of my free time these days. I saw the Rubik's Cube first, when I was in school. I could solve no more than a single side and thought that that was the best that could be done. Until when in college, a friend could solve this with ease. While solving the cube, after solving the two opposite sides, he would solve the rest without having a look at the cube. It used to fascinate me a lot until he explained the whole idea. He could also tell if the cube was assembled incorrectly after a certain amount of moves. I picked up the tricks from him then but have forgotten / out of touch. Have been taking close to twenty minutes to solve it. Will try to improve and learn some new tricks.