It's a fact that many of us are critical of ourselves when there isn't a thing we should criticize! Of course, there are always things that we can improve about ourselves but those things are not valid enough to examine ourselves in the mirror and not love what we see both inside and out.
Maybe growing up as a child, you were bullied. Too chubby, too skinny, too many freckles, glasses or even braces. Me personally, I was bullied because of my complexion and sometimes my high forehead, but guess what? I love every part of me. I love my skin tone and my high forehead, along with my high cheekbones which makes my features distinctive. The point I'm attempting to prove is, ALL of us are BEAUTIFUL and we deserve nothing but love. However, we must first love ourselves and all that we are and embrace every aspect of our being.
According to the Wikipedia self-love is caring and about loving oneself, accepting responsibility for oneself, respecting oneself, and knowing oneself (e.g. being realistic and honest about one's strengths and weaknesses). He proposed, further, that in order to be in a position to truly love another person, a person needs first to love oneself in this way.
Self love is not narcissism, as narcissism is vanity, so don't convince yourself that if you begin to stop and stare at yourself in the mirror and admire yourself more, your'e becoming conceited. Matter of fact, a great exercise is looking into the mirror every evening before retiring to bed and stating to yourself the thing(s) that you like about yourself. It's called the mirror exercise and you can find it here.