Self-love isn't just about telling yourself that you love yourself in front of the mirror. I mean that helps and if you do it until you believe it, it will become true. But another key to self-love is being your own best friend. Think of how you would talk to a best friend going through a rough time. Think of the things you would say to someone that you love who was feeling down. That is how you should speak to yourself. Be your own cheerleader. If you're having a bad day, tell yourself it's going to get better, look on the bright side, cheer up...
Instead of putting yourself down or berating yourself give yourself a hug and tell yourself everything is going to be okay. That is self love.