Okay so people keep saying "confidence" but if you are super ugly (I'm sure you're not) but like SUPER UGLY... confidence isn't going to help you. Just take care of your appearance, do your eyebrows if they crazy, where a bit of makeup if it makes you look more put together, do something nice with your hair, make an effort. Some are lucky and don't have to make any effort to look good, but not everyone is that lucky. Also, a nice smile helps. Stay fit.
Well everyone has a different opinion on what is pretty. Things like shiny hair and clear skin are things a lot of people like. Confidence, a bright smile. Just think of what you think is pretty and go from there.
The best way is to love yourself first. Find something you like (like your eyes, smile, hair, etc.) and expand on that slowly over time. You can experiment with looks, maybe try a little make-up. Not too much, but try different eyeliner styles, mascara, and whatnot. Maybe try a lipstick that suits your complexion. You can drink a lot of water to help your skin, wash and moisturize your face as well.
Be confident and you'll attract anyone you want ! Just never mistake confidence for cockiness.