Low self confidence ... Help ?

Soooo , I have really low confidence ! I never think I look good , and even when I'm in a bathroom , I try to avoid looking in the mirror because I know I won't like what I see. I wear some makeup to try to cover up my flaws , but I just don't think I'm that pretty . People will compliment me , but I usually think its fake . I don't know how to give myself confidence , any tips ? Thank you very much !