Be really good at sports or have sex with the teacher.

Always be a teachers pet, be attentive and be front in studies.

Hitting the books with vengence.When people were munching pop-corns infront of Tv ,I was munching Organic Chemistry.
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When Kids had the PC joysticks in their hand, I had the pen figuring our Geometry.
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When people were busy on a roller-coaster ride,I was figuring out the rotational torque on those who enjoy the ride.
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There are many other easier ways to get grades but, getting them the proper way is no kid's play.You have to grow up early.

Study. Get involved in the class. Look, you have to do it anyway (or at least you have to go through the motions) and it isn't so much the information you learn, although that is important, but how learning these various subjects TRAINS YOUR BRAIN.

By studying smartly!
1. Study daily.
2. Take good notes.
3. I memorize things easily, so if I had to memorize, it didn't take long.
4. Get enough rest, especially before tests.
5. Know everything that will be on tests, so then there is little pressure on you during the test.

Man, do what the top kids do. Ask question. Read book. enjoy challenges. Just take prep classes.

study study study