That's a really good question, and a hard one to answer. I've played soccer since I started school, and in high school it gets hard to do well at sports and your classes.

it sucks but the only surefire way of making sure you do well in both is by making some sacrifices and through time management. Getting assignments done early is a huge help because sometimes you have conflicts between school and sports. try to work out a plan, especially when you get a big assignment.

just do what i did. if you have an understanding coach, explain to them that your classes are real important, and you need to focus on them first. that should be able to get you out of any practice if you're in a crunch because it looks like you're being responsible. that's how you take down the man!