I wanted to help, so I just looked in my bookshelf because I didn't know what to say.
How would she honestly describe herself in positive terms? �(an excersize in I found in a book)
Figure that out and reinforce that perception.
Build on success. �Support and reward small steps and progress. �Catch the child doing something right-frequently. �The frequency of re-enforcement is important. �In this case you're reinforcing the positive way you think she would see herself.
Can she distinguish between liking and being friends with someone?
(from the same book)