Taking care of yourself, respecting your limits, and having a solid network of family and friends can help with having good self-esteem.
There is nothing wrong with wanting to be beautiful, or taking the time to care for your appearance. On the contrary! It is even a sign of good self-esteem. It is a way of telling yourself and those around you that you are worth it. The important thing is to find a healthy middle ground between recognizing your qualities and not being too hard on yourself.