The Haislet book has worked wonders for me. Put gloves on my hands and I'm a dancer, I can veritably glide around the ring.
Seriously, he has the simplest, most straightforward, most effective explanation I am aware of. The exercises are pretty damn dull, but give it 10 minutes a night for a week or so and you'll notice the difference.
Also, consider the important role that punching technique plays in your footwork. Your balance is so, so important.