looks is what initially attracts the guy, there won't be a relationship if they are not physically attracted to each other right, so you could say that is important. But you need to have a personality which suits the guy. For example a shy guy will be instantly attracted to an out going girl(for me anyway hehe). The personality is major!
There's a number of things that make a girl pretty for me, but what I notice first is a nice smile (genuine smile, the kind that lights up a room. not an awkward forced smile.)
everyone is different and what makes a girl pretty for one person won't necessarily apply for someone else.
I think the most important thing is to just be yourself and not over do it. too much make up in my opinion doesn't make someone pretty. nothing wrong with a bit, but when you can clearly see they have too much, it's a bit of a turn off for me.