DISCLAIMER: This is based upon my high school. That's all I know, all I can write about. Your high school may be different and then none of this will apply. But I suspect that in most situations, at least some of it will...
In response to some of the negativity...
My best bit of advice is, if you feel confident enough (see Woundweavr's writeup above), try to befriend the really popular people. It's been my experience that the only moderately popular people are the scummbags that hate everyone different from them. Talk to the folks who get "Class favorite" in the yearbook (in my yearbook, it's called that, it may be different or nonexistant in yours). They don't get to be class favorite by ignoring or hating people. They are the class favorite because they get along with everyone and everyone gets along with them, for the most part. Obviously, if you're a real asshole to them, this doesn't apply.
If you're not friends with these people, stay away from the folks lower down on the popular branch of the high school tree. They are the ones most likely to humiliate and make fun of you. I imagine they do this to try and get higher up on the popularity scale. But guess what? They won't, not without being decent to everyone. That's what is required to be the most popular.
Now, the further down the popularity chain, the more assholes you find. There are probably many, many exceptions, but this is usually the case. Don't try to befriend every last person in school before you are friends with the folks at the top. After that, well, if they like you, you must be a pretty great person, right?
I'd also like to add that I'm not saying you should conform. Be yourself.. I wrote this from my experience, which was I was quite shy in addition to being a computer geek my freshman year. My junior year is now almost up, and I am enjoying high school much more now, while staying a huge computer geek.
DISCLAIMER #2: Yes, it's full of generalizations. Sorry. But hopefully it will help one of the folks to whom high school is a bitch. I've done the best that I could in writing this up. It should also be noted that I practice what I preach and am having a great time in high school as a direct consequence.