Squats, step up’s, etc with weight. I’m fortunate enough to have been getting lessons 2x/wk, and my footwork has improved a lot. It feels like it’s 20% mental and 80% my thighs - like a crab scurrying sideways :) When I watch better players (like my coach) they anticipate where to move earlier (mental) and also move quicker/more efficiently. Exercise will help with the later, but the mental part is only going to come with lots of experience