Just to let you know.
Wrestling.
Is.
Effing.
TOUGH.
You will never find a more physically exhausting sport (although MMA is pretty close). You'll like wrestling; it's so much cooler than any other high school sport, but get ready to be in the best shape of your entire life. I've been wrestling longer than I've been doing stand-up and submissions, and I still say that the fight for the takedown is THE most physically exhausting part of combat. Forget punch flurries, forget the fight for the submission. If you're fighting an equally skilled wrestler for the takedown, it takes so much out of you. It takes all of your strength, and all of your speed. I have guy at my gym wiho tap from fatigue when they roll with me, because of the shape I'm in from high school wrestling.
Lift weights. And when you do cardio, do anaerobic routines. Very important. Wrestling matches are only 6 minutes long, so trust me when I say this, your opponents will not be pacing themselves. They're conditioned to go all-out for those 6 minutes. (Although I will say, in my experience, wrestling coaches aren't always the most knowledgable when it comes to cross-training for conditioning. Don't leave it up to them. Take the initiative to learn better running routines.)
When you step onto the mat to wrestle, be prepared for an all-out drive. You need to be warming up before your match, and when you go out to wrestle, you should have sweat dripping off of your forehead. Trust me when I say that. That is of major importance. If you're sitting around before your match (you'll either be tired from a full day of school or from getting up early to go to the meet), you'll be yawning when you go onto the mat, and you'll get your ass kicked if your opponent is ready. So be warming up, and NEVER be intimidated. That is the absolute worst thing. Forgive me if I'm wrong, and I am completely not a racist, but I am guessing, based on your description, that you are a slightly short, kind of out-of-shape white kid. If you step onto the mat with a muscular inner-city black kid, DO NOT be intimidated. I have nothing against African-Americans; I'm friends with plenty of them, so please don't misinterpret that. But sometimes, for some reason, inner-city black kids just intimidate suburbian white kids. Never, ever let your opponent's physique, skin color; nothing should intimidate you. You need to treat every opponent like he threatened to kill your family, robbed your house, kicked your dog, beat up your girlfriend, and is trying to steal something from you. Of course, no punching or biting, but instead, use legal moves to beat his ass. Use nasty tricks (that are legal) like your chin or crossfaces. Crossfacing is a big skill in wrestling that carries over nicely into BJJ. But seriously. Never doubt yourself for a second, and even if the kid is jacked out of his mind, you need to believe that you can beat the shit out of him.
Regarding that, let me tell you a little story that happened to me last year in my sophomore year of high school wrestling. Now, I'm not the most amazing wrestler, but my coach has told me that I have really good potential, and I'm really working on it. My biggest problem in the past has been the different tricks of competition, because I never did sports until 8th grade. I would come out onto the mat not warmed up, and I was easily intimidated. Towards the middle/end of my sophomore year, I finally started figuring out competition, and I never lost a match after that. We were at a meet in Lowell, and I wrestled two kids who I truly believe would have beaten me had I not figured out the mentality I should have in competition. The first kid DEFINITELY outweighed me. JV can get fucked up like that. Everyone on my team told me, he must've weighed at least 185, and I was 160. I didn't get intimidated though; instead, I ended up getting on his back, and when he wouldn't go over, I started crossfacing the hell out of him. Ended up pinning him in a Saturday Night Ride (wrestling name for a mount). I always instinctively move into the mount because of BJJ. lol. So anyways, my next match was against this big inner-city African American kid. I know that if this had been earlier in the year, I would've been intimidated because of a stupid reason like looks. Instead, I looked that kid in the eye, and within maybe 5 seconds, I got a single leg, slammed his ass down on the mat, and ripped him up in a half nelson as tight as I could. He started gagging and saying "GET THE FUCK OFF ME, I CAN'T FUCKIN BREATHE." I loosened up a little bit, to be nice, and he started squirming away, so I told myself, screw that, and just squeezed as hard as I could until he was pinned. The kid was so mad that he didn't even shake my hand, but later on he came back and apologized. Still, the JV squad was giving me high fives, and were telling other kids on the team "Thornton beat the shit out of this huge black kid!" Not that we're racist or anything. It's just the intimidation factor at work.
Regarding the comment about wrestling being more about muscle and less about technique; it depends how you look at it. Compared to BJJ with a gi, yes, wrestling is WAY more about muscle. Compared to No Gi BJJ, wrestling is a little bit more about muscle. But wrestling definitely has technique. You still NEED technique, and I mean need. You will not get anywhere with just muscle. One thing people don't understand about wrestlers is that there's more to us than serious conditioning and strength. Wrestlers can actually be not that strong, but when you fight them, they will seem really strong, because they can hold a position really well. Wrestlers are very difficult to sweep or reverse from a mount, because they're really good at balancing. After all, think about it; the entire sport is putting someone on their back. It's going to be hard as hell to beat a wrestler at that game. But wrestling requires lots of technique, and balance is going to help a lot, too.
I recommend you do what I do when I'm learning martial arts. Buy a book or instructional video. You won't be an awesome wrestler just from reading a book, but I guarantee it will help you. You'll be ahead of the game, and you'll have a better understanding of the moves.
www.budovideos.com has great books and videos. Check out the wrestling books and videos. (They have stuff by Randy Couture and Darrell Gholar; but I'd recommend getting an actual wrestling instructional. The cover or case should have wrestlers in singlets and headgear.)
So remember. Wrestling is a tough-ass sport. During the first few weeks, you will be dying. A lot of good coaches will make the first few weeks really hard, to weed out the wimps. Don't be one of them. If 60 kids join the team, 60 kids have the potential to make the team; the ones who quit are the ones who give up. So never give up, because you can do it. And I promise that you will get in better shape, and you will get tougher. Remember to train hard; you need to train like you have the biggest match of your entire life coming up. Lift, SPRINT, swim, jump rope; make your workouts short and INTENSE.
http://www.t-nation.com/findArticle.do?article=251run2 These running routines are great for wrestling. Follow their program.
When you step onto the mat for competition, remember to be warmed up and sweaty, and be ready to physically impose your will on your opponent. NEVER be intimidated by ANYONE. Not even if it's King Kong. Always believe that you can and will beat the hell out of your opponent, and that you are a madman. Always be ready to go 100%. If you go even 99%, someone will beat you because they were going that extra 1%. Give your heart and soul in every match that you wrestle in. Good luck, and remember the most important thing: have fun. When you're drowning in sweat, and your shirt is soaked from bloody noses, you might not think you're having fun, but what's fun is the entire journey. Wrestling will make you a different person, and hey, instead of playing a pointless game like basketball or winter track, you get to wrestle.