Jumping rope is the easiest way to effectively work on your footwork. Look, there are some simple things you can do to fix footwork issues. The first is to jump rope, also watch yourself in the mirror. Practive stepping, your feet should always be underneath your chest. If you step forward, your back foot needs to slide immediately behind your lead. Vice versa for stepping back (never go straight back, but rather at an angle.) Sideways steps are easy, just remember the foot that you lead with is the closest to the direction you are moving. (Circling left, lead with the left foot). You can also tie a rope between your legs at the appropriate distance if you are spreading your feet too far.
All that will be helpful. However, if the issue is balance, and smothering your shots, my guess is you are making a few common fundemental mistakes.
1.) you are standing too square. Make certain you are
at the appropriate angle with your feet and that your hips are in line with your feet.
2.) You aren't bending your knees. Don't stand up so tall. The more you bend your knees, the better power you'll get in your shots. Just remember to keep your feet under your chest.
3.) Your posture is bad. Keep your back straight, bend at your knees and not at the waist. Turn your shoulder over and pivot off your feet. Your hips should turn.
Try this drill, its easy, but it won't feel right if you are off balance. Stand in your boxing stance, step forward with your front foot. At the same time you step, you bob to your right. (Assuming you are an orthodox fighter). As you bob inside, feel the front of your left foot "tap" the floor with the right part of the ball of your left foot. (Hope I'm not making this sound too complicated, but it'll be easy if you just walk through it.) Next, bob back to your left, stepping again, but step with your toe about an inch to the left, touching down the left part of your left foot. Bring the right sliding directly behind. Step foward in this fashion, bobing, weaving and stalking in a straight line. After you get this, try to do the same drill moving backward. (But still doing the "tapping" movement with the front foot while stepping with the back.)
Hope this helps some, let me know if not and I'll see what else I can help with if possible.