Studying Method

I think that doing well in school has a lot to do with your attitude and the amount of effort you are willing to put in.  Every day, my guess is that you have about an hour of each subject.  You might not have every subject every day, but either way... every day, I would come home and review what you learned that day in class, even if you think you know it and you don't need to.  Of course, always put time into your homework as well.  Take a few hours each day to dedicate just to your homework.  If it helps, start to study with a friend that is also serious about his/her studies.  If you find that there are one or two subjects are harder than others, I would go up to the teacher, and just talk to them after class.  Let that teacher know that you care, and that you are willing to do anything that they suggest in order to be sure that you succeed in that class.  I'm sure that your teachers will want to help, or just to be supportive.  Friends are also great resources, if your finding that something is hard.  A friend can explain something to you, or a parent, or a teacher after class.  Turn to those that you know care about you, to those that want to see you succeed.  Believe me, your teachers want to give A's.  Good luck! 

Great that you want to improve your grades and that you want to be smart.  Let's focus on grades.

1.  Ask each of your teachers that you are interested in their teachning and classwork and what are the top three items in class and also for work that they expect from an excellent student.  If anything they say seems unclear, ask them for general examples.  Then act that way and include those items in your work with your own work.  If you are shy to ask your teachers this, ask one of your parents to go in with you!  Teachers will appreciate that you are interested in their work and the class.

2.  Practice makes perfect.  Old saying but true.  Just keep at it.  If your approach isn't working (let's say you can't figure out a math problem), take a break for 10 minutes, practice breathing during that time, after ten minutes are up, go and figure out a different approach or who to ask about how they did it.  Then do that.

3. Set aside time for homework before dinner or an hour after dinner.  Always an hour a day.  Even Saturday and Sunday.

4.  "Birds of a feather stick together".  It's good to have a variety of friends.  You want to know how to get good grades.  Find out who gets good grades and study with them if they do it in groups.  If you wanted to be fashionable in your school, you think you dresses the best, find out where they find their stuff, etc.  Do the same for grades...go find the high grade kids and copy their study habits that work for you.

5.  Drop the slang and improper English when talking with adults.  No one will take you seriously if you don't sound as if you know what you are talking about.  Learn to speak correctly.  Find audiobooks if you have to learn how to speak correctly.  Or get Elocution lessons.

If you tend to understand things better if you see them on a diagram, try mind mapping.

As for grades, grades on their own are worthless. Seek skills how to understand things and skills how to apply your understanding in a variety of life situations, not some hollow grades.