first practice stayin on the balls of your feet. Second practice circlin around the ring while on the balls of your feet with your guard up. practice moving forward and backward with balance. Then practice side steps. Then work up to combining footwork and feints with strikes.
Jumprope also helps alot, most people are too lazy to train footwork sepratley, so use it as part of your warmup.....
Id also say take a salsa class or talk to some WTF TKD guys about footwork..