Footwork improves with daily, deliberate practice of short, balanced steps that keep your stance intact. Use ladder and line drills, mirror work, and shadowboxing with attention on staying in position rather than on moving quickly.
Every step should leave you able to punch, defend, or move again immediately. That means keeping your feet roughly shoulder-width apart, never crossing them, and moving the near foot first in the direction you are travelling. Steps that are too long leave you unbalanced and unable to fire, which is the most common fault in beginners.
Footwork is a skill, but it draws on calf and foot stiffness, single-leg strength, and lateral push-off. Pogo hops, single-leg calf raises, lateral bounds to a stick landing, and lateral shuffles all support it. Skipping develops several of these at once, which is why it remains a staple.
Practising quickly with a broken stance simply makes the fault automatic. Work at a speed where the stance holds, then increase gradually. Speed that costs balance is not usable in a fight.
Ten minutes daily produces far more change than an hour once a week. Footwork is a motor skill, and motor skills respond to frequent, attentive repetition, as discussed in Agility and Change of Direction.