You know what they say about first impressions, right? You only have one chance to make one. And this is completely unfair.

But you also know what they say about life. It's unfair. And that seems just awful if what you focus on is how you will be walloped by the chapped, uncaring hands of fate.

There's a flip side to this injustice, though: It can work in your favor.

All you need to know is how to communicate well--both in what you say and with what you do. It sounds simple--but of course, it isn't always so easy.

And the people who have the hardest time here are students going back to school. I know this because I used to be a high school teacher, and I saw it firsthand.

Many adults love being hard on students. I get really sick of hearing how kids today don't know anything, don't have any discipline, and would never have survived in an Era Without Pagers. I don't believe this for a minute, much as I respect healthy concern for the education of kids.

Kids today know a ton--it's just different stuff from what their parents and grandparents know. Kids are generally much smarter about using technology. Ask any parent and you'll probably hear, "Yeah, my kid knows way more about computers than I do."

In today's world, understanding technology is a lot more important than being able to recite where the world's highest waterfall is (although that sort of knowledge and quality time with Alex Trebek can help make you famous).

So, if kids are so smart, then why is going back to school so hard? It's because there are two groups kids need to impress: their teachers and their peers.

Quite often, what makes a good first impression with one group doesn't go over so well with the other. For example, while a student would look at a midriff-baring T-shirt and think, "She's got a nice innie," a teacher will look at it and think, "She's got a lot of nerve showing up to my class half-nekkid."

And, while a teacher will look at another teacher's necktie and think, "Now that's a nice, manly accessory," a student will see it and think, "May I never have a job where I have to have one of those. Not without stock options, anyway. What a sucker."

It goes beyond clothes, of course--there's what you say and how you say it. And since you have about 10 seconds to make your opening statement to your teachers, you might as well do it right. After all, most teachers have already seen the extreme statements before. Marilyn Manson isn't that different from Ozzy Ozborne, who isn't that different from Alice Cooper.

So what's a student to do? Easy. Follow these four tips on how to dress, how to talk, how to win the teacher over ... and how to be.

1. Dress like you mean business
Specifically, don't dress to impress your friends. You don't need to. They're worried enough about impressing you. How can you tell if you're falling prey to this trap? Look at your clothes.

Here's a little story about clothes that send the "I'm a dope" message. Just last week, on a 80-degree day, I saw a teenage boy with his girlfriend. She was wearing shorts and a T-shirt. Looked perfectly fine. He, on the other hand, was wearing a wool ski cap pulled down to his eyebrows. He was also wearing pants so low-slung he couldn't walk without holding them up with his thumbs.

The key here: The kid's fashion statement was getting in the way of comfort and mobility. This is the sort of thing that cracks adults up--and not in the way you want. The message you're sending with outfits that don't make sense is that you care so much about your image, you've lost touch with reality.

2. Be a kid, but talk like a teacher
Boys aren't the only ones to do goofy things. Many girls--and lots of women, too--make an unfortunate habit of ending sentences with a question mark. Even when they're not asking a question. It sounds like this:

"So I was at the bookstore? And this guy? He came up to me? And I was like...." Ugh.

Even Terry Gross, the noted interviewer on National Public Radio, does this. To many people--this former teacher included--it makes girls sound like wimps.

To find out why so many girls and women talk this way, I contacted Deborah Tannen, a Georgetown University linguist and author of You Just Don't Understand, a book about how men and women converse differently. (Tannen is also author of The Argument Culture.)

Tannen says that young women often end sentences with question marks because other young women do it--and they want to sound like their peers. The underlying logic of the practice, Tannen says, is to encourage a response. Even if it looks like insecurity (or wimpiness), that's not the intention.

And that's my point: Don't let your clothes or your speech patterns say something you don't want to be saying.

This sort of thing reminds me of a great book I read: How to Speak Dog, by Stanley Coren. It answers the age-old question of why dogs and cats just don't get along. One reason? They speak different languages. And I'm not talking barking and meowing.

According to Coren, when a cat sticks its tail up, it's saying, "Hi. I am feeling friendly toward you." But when a dog does this, it's saying, "I am the boss of you." A cat trying to be friendly can really make a dog mad--usually with bad results for the cat. In school, students are the cats, by the way.

3. How to win the teacher over (and get good grades)
The secret here is to neither suck up to the teacher, nor focus on grades. Yeah, I know. Parents and teachers make it sound like grades are the Most Important Thing Ever. But grades are really stupid. That doesn't mean grades don't count. They do.

Grade-obsession teaches kids that success is easily and regularly measured. But life just doesn't work that way. Once you get out of school, you generally won't face weekly exams. You won't get little pointy A's telling you you're doing a good job. You might get performance evaluations at work every six months. But these don't mean promotions every year (like going from 9th to 10th grade, which is pretty much automatic as long as you show up to class).

What you want to focus on instead is the stuff you're learning. Don't worry if you can do something or not. You will be able to. Lots of other students have taken these classes before you, and if other kids can do it, so can you.

Besides, you have a secret weapon here: If you don't understand something, ask your teacher. Teachers LIVE for this. And often, they will let you know in not very subtle ways just what's on that test. Instead of spending one second worrying about your grades, spend that time understanding the subject. The payoff will come--both in class and later in life. Because that's how things really work: If you don't know your stuff, you won't succeed.

But wait, isn't that trying to be the teacher's pet? Nope! The teacher's pet wannabe flatters the teacher without really working to understand the material more. It's that whole apple-for-the-teacher thing. It doesn't work. My advice to you: Forget the fruit; forget the flattery. Teachers just want to talk about what they're teaching.

4. How to be: anything but a chicken
Lots of kids find things they really like to do in school. But they don't do them, because their friends aren't doing them, or because there's no class on the subject, or because their parents tell them it's not a good way to make money. If there's something you really like to do, find a way to do it at school. This is the entrepreneurial spirit--and people who have it tend to have the most interesting lives.