Take subjects that challenge you and are varied. Hermione takes more challenging and varied subjects than others, however the result is that she comes out with a well-rounded knowledge. However be wary of a heavy workload, while Hermione is very good, even the best of people will suffer under pressure and stress. Hermione takes so many subjects in her third year she becomes stressed, irritated, snappy and upset due to the immense pressure of stress due to her school work. Don't take a lot more than you can handle, just try a tiny bit more, like an extra non-fiction book, an extra page of a textbook, stuff like that.
Try to get straight-A's in school. You can achieve this by doing your homework, studying for tests weeks in advance, doing extra credit assignments, and finishing projects on time. Hermione studies whenever she gets the chance. When a teacher asks a question, stick your hand up as far as it will go (even if it means standing up) and try to get called on. Just remember not to be too annoying, otherwise you could be sent out of class, get detention or even worse, a bad mark or grade on your report card. Doing this at every question will show your teacher that you are paying attention and are trying to get good grades. You want your teacher to say, "anyone else besides (your name)?" Hermione would be delighted that the teacher would say that.
Always ask for more work or extra credit work if you've finished your homework early. As Hermione once said, extra credit is always nice to have just in case, it shows your immersion in the subject and as an individual you reap the benefits of knowledge and effort. If you finish your schoolwork earlier then everyone else, start on your homework. If you ever feel like you didn't get enough homework, go up to your teacher and ask for extra work. If she doesn't have any, ask her if she can start early on a new project. Your teacher will be shocked.
Pay full attention to the teachers and ignore kids who talk to you during class if they're not supposed to. Shush them real big and keep your eyes on the teacher. Turn a little so you're not facing them. After class, go up to them and say in a rushed voice, "It's not worth getting in trouble during an important lesson to talk about video games!" and prance away.