Start with a smaller heel, and practice. Practice walking, practice stairs, and for the love of me, practice turning. If you're going to be dancing, practice side to side movements. When you're walking, remember to keep your legs straight and as close together as possible. With each step, point your feet as straight in front of you as you can. Start slow, and you'll gain confidence as you practice.
If you're going to walk on stairs, use a rail if there is one, and don't give in to the the urge to only walk on your toes.