It definitely does. Not only the way you look, but specifically the expression on your face. If you have a wide-eyed sort of expression on your face, like you're lost, people will automatically come up to help you. If you look a little glum, people will come up and ask what's wrong -- especially if they already know you to be a happy sort of person.
The acne DOES fend people off in some cases, though not always. If you can look confident even on the days that you have acne or whatever, people will be attracted to you. You make the acne look cool. (Yes, that sounds weird, but I've actually seen that happen.)
You can be very pretty but have low self esteem, which makes you look dull. On the other hand, you can be very plain and have a high self esteem, which makes you look radiant. The conundrum is when a very plain girl shows TOO much energy or a very pretty girl tries to mask low self esteem with snobbery or standoffish behavior. Both are unattractive.
What seems to escape the radar are the girls who are pretty and nasty to others. They possibly have the LOWEST self esteem, and put others down before others put them down. They're insecure about some aspect of their lives and are unable to deal with it in any other way than to be bullies.
sadly, attractive people are often treated better than unattractive ones. that's just how it is. however, personality plays a part here too. if you let this affect you, you'll just push away people who are willing to know you. if someone doesn't want to hang around you because you're not that attractive (which of course you are :) ) then they're just not worth it.
yes it makes a lot of differences example: I used to be chubby, I wore unflattering and illfitting clothes, never did anything for my poofy hair and kinda looked like a chubby boy. now I am thin, toned, have a great haircut and have learned how to style it, became a fashionable girl and started wearing more feminine clothes and now I look pretty. when I was ugly I had maybe 5 friends none of which actually did things with me outside of school, I used to be unpopular and could never get a boyfriend. now I am very popular, everyone loves me, I have more friends than I am willing to count, I am incredibly busy and tons of guys like me. we are a materialist and superficial world.