You would start by paying close attention in class, doing your required homework in a "professional" manner and to the best of your ability and admitting you don't understand something - if you don't understand.

The fact that you posted this indicates you are very responsible so I'm sure this will be second nature to you.

Good luck.

What an admirable attitude!
You will not only make your parents proud , you will be helping yourself get through life

It always helped me to read everything about what I was studying twice.
Take notes on everything, writing it down helps the memory.

If you're not sure ask!!

And if you are having trouble ask the teacher what you can do , to do better in study.

Is there a area you are having trouble in ?

As your parents to help you set up a good place to study and set times to study

Start with a good night's sleep each night so that you can be well rested and ready for school after a healthy breakfest. Take an hour or more if you prefer or if it takes longer to do your homework each day. And also do some extra homework even if you don't have any. (within the 1 hour or something like that you set aside to do school work)

And yes like the above posters say, if there's something you don't understand ALWAYS ask until you understand it completely.

The secret to learning something is repetition and time.