For obliques, if you go to a gym, they have machines for that. Or basically just a stand. You sit sideways on it, at an angle, and basically do situps, but sideways. Then turn around and repeat. You can hold a weight with one arm and dangle it for increased resistance. For better definition, running (or something of the like) is the best way to increase definition. And healthy diet. Lots of water, soda is bad.
