If you wax and then rewax the same place right away because you didn't get it all the first time, you may bruise the skin. Also, not holding the skin taut when pulling off the wax strip can pull that delicate skin out and bruise it like that.
Only wax an area once: if you don't get all the hair off, wait a few hours before trying it again. Don't pull the waxed strip off without supporting the underlying skin with the other hand: aside from bruising, you may get bleeding and an incomplete wax.
