-Piercing knee with high guard.
-Step back only with your front foot and body, the rear foot stays put. If he follows, your rear leg should be in a striking distance.
-After a check, put down your foot a little further, not just down.
-If you move your front foot first, your opponent will see it. If you move your back foot a little (no switching, and don't compromise your balance) you may trick your opponent.
-Feints, but instead of the actual strike, you move. (but like all feints, you have to make him scared of the actual strike, so you must do some damage before)
-Pressure and footwork to put him on the ropes/corner.
-Switch kick with the a little hop forward (needs a lot of practice)
-Long jab to keep his guard up shielding his eyes from you footwork. You may leave your hand hanging a bit in front of his face, but it has risks...
-Teep with the front foot, while you "hop" with the rear (needs a lot of practice)
-Flying knee (needs practice)
-For a south paw: Step outside of his lead foot, watch out for his left elbow and switch kick/knee.
Watch lot of fights from pros, and just concentrate on how they do it. I don't find it that hard to close distance in MT, cause usually the opponent doesn't move back a lot. The mentality is to stay block and trade, not so much to evade.