Painting yourself is something I think all artists should do. It teaches you to love yourself and to look at your own beauty.
Everyone looks into the mirror and sees flaws no matter what they look like, this is what it means to be human. We are blessed and cursed at the same time. We find something we love about ourselves, only just to find something that we hate. This is ok because polarities must exist. What it comes down to really, is the self acceptance of the good, the bad and the ugly.
When I paint my self portrait, I am constantly reminded that I am beautiful, because it is not just what is on the exterior but what lies beneath the surface.