Photography Tips and Tricks? (preferably nikon d90)?

I'm a highschooler and starting out in photography. I'm wondering if you could share your wisdom!

You lshould have a textbook that will tell you much of what you need to know. Read it. Study it. Especially exposure and composition.
Study the work of other photographers and artists. So much is lighting.
Don't shoot like anyone else. Every around you standing shooting a horizontal, you squat, or kneel, of climb up on something to get a vertical with a different angle and more impact.

Go to a book store and find the book "Photography" by London and Upton. Read it!

Visit a local professional photographer and ask if you can clean his windows, sweep the floors, empty trash, etc in exchange for some photo advice.

With every assignment, your goal should be, "I want to blow the socks off my teacher!"

Since you never actually said you are taking a photography class I'll assume you aren't and that you don't have any photography books.

First off, any photography book that explains how you get proper exposures is going to really help you but you can also find any of that info online too and there are great tutorials online. One place you may not have thought to look up photography tutorials, youtube.

Terms to look up and learn: exposure, shutter speed, aperture, depth of field, ISO to start. Forums are also great places to ask for advice and to share your work. There are camera and brand specific forums and there are subject specific forums and beginner's forums. Start at dpreview.com to find a little bit of everything, including camera and lens reviews.

Now some shooting advice. Don't just use continuous shooting mode unless you have a good reason. It really handicaps a photographer to start relying on burst shooting to get a good shot. Instead, take your time and look at the scene and think about it. Is there anything you think it could do without? Poles that look like they're coming out of people's heads? Clutter? Watch for those things and you will see yourself making better photos. And more of them too. Have fun.

Since you are just started out in photography, do alot of googling.read books
Become a member to photography forums like this one.http://www.photographytalk.com/ You can find out alot from photography forums, photography sites, and books.
Google "rule of thirds"
Understand lighting, it's the most important thing in capturing an image.
Learn your camera.