Seconded. If you've always struggled in school, but are now looking to put in a lot of effort, show your teachers that you're putting in a lot of effort. Ask for help. Ask questions. Be obvious and up-front. Believe it or not, most teachers became teachers because they wanted to help people learn. They wanted to be a positive influence on the lives of young people.

Everyone on staff at your high school wants you to be a success story. Help 'em out by sucking down their time and being up in their grilles. They'll love it.

A word of caution - you may have to scale back - perhaps even outright ditch - your posse. Being a slacker burnout is such an identity that it's hard to try hard and roll with your crew. Speaking from authority here - the burnouts were my posse and I got a 1530 on the GREs. Success likes success and you will likely find it a lot easier to keep trying harder if you surround yourself with people who are willing to try hard.

Good luck. There's every chance this year will be transformative for you... if you let it.