Oh and learn to feint a lot. Feinting instead of trying to actually land everything hard is hugely important for scoring with combos, it takes forever to get good at, and you don't see it much in mma. When I started really focusing on feinting that's when I started finding myself actually making combos work.
Member of DaJoGen MMA school under Dave Hagen and Team Chaos fight team under Denver Mangiyatan and Chris Toquero, ran out of Zanshin Martial Arts in Salem Oregon: http://www.zanshinarts.org/Home.aspx,