Most Helpful Guy
First step: Don't call yourself ugly.
After that, if there's anything you don't like, work to improve upon it; unfit? workout etc. Nobody's ugly in this world, what's ugly are the people who make you feel as such. Everyone has remarkable potential, you just have to find yours.
Most Helpful Girl
I have stretch marks. I have the craziest hair that would have been perfect for the 70s, not so much in my life. It's the dullest shade of reddish brown imaginable. I have super small eyes, a huge forehead.
My point is everyone can see their "ugly". What they can't see is all of their beautiful, their own awesome. Kinda like butterflies, they can never see how gorgeous their wings are.
Find your pretty. Find the parts about you that you love. Focus on those every day and slowly try to start loving the rest a little at a time. This is a mentality that has to change before you will start to love yourself. And not that you need it, people are awesome, but if dying your hair makes you feel like a rockstar... dye it. If make-up makes you feel pretty... rock it. Find yourself, then find your pretty. You see all of your flaws, everyone else sees your gorgeous. Especially at such a young age. Everyone goes through an awkward phase at some point. Keep your head up.