Doing well in school is simply a matter of organization. Intelligence also helps, but organization beats intelligence.
Here are some tips:
The following will guarantee you no less than an A- on an essay exam:
Take good notes in class. And you read the textbook, take notes in outline form. So you're only going to read the textbook material once, but the notes will reinforce what you read and give you material to use in studying for the exam.
Several days before the test combine your lecture notes and textbook notes into a master outline. A couple of days before the test, get one or two other people who want to get As on the exam. Get together and grill each other on the master outline until you have it memorized. Be relentless: "what are the three ways Plato says we can be mistaken? What are the five principles of operant conditioning?" And so on. Look at it this way: you're in a play, and the outline is your script. The test is your performance. So memorize the script. You wouldn't go on stage without knowing your lines, and you shouldn't take an exam without knowing all the material.
So when you walk into the test, the question is not whether you know everything, because you already know everything.
Now, when you take the essay exam, have a piece of blank paper. Before you write your answer, write a brief outline of your answer on the blank paper. When you're satisfied with the outline, write your answer, looking at the outline. That way you end up with an answer that is complete and flows logically.
Also, prepare what I call the "flagship" question. With most essay exams you have a good idea of at least one question that will show up. Put some extra effort into that question. Quote St. Thomas in Latin. Memorize a few names and dates. With the flagship question the idea is that you're going to blow your teacher away. You're going to show the teacher that you don't just know the stuff, you've MASTERED it.
When it comes to papers, make sure that you do your work up front. As soon as you find out that you have to do a paper - THAT VERY DAY - go to the library and look at the books that are available on that topic. Don't read anything; just see what is available. Then the next day start your research. Again, don't spend a lot of time, but become familiar with the material. When you have a topic, start on the paper. The key to a good paper is to start early enough so that time is on your side.
Now, a lot of the other students will start a paper a week before it is due. But not you. Your paper will already be finished then, because you've done your work up front. By starting early you will make sure that you have enough time to do a quality paper, with perfect grammar and spelling.
Using these techniques I graduated with highest honors from an expensive liberal arts university, 3.97 GPA.
If all of this sounds like a lot of work, it is. But that's because doing well in school takes a lot of work. BUT - you're actually going to spend less time than others, because your study time will be so much more efficient. You're not going to have any last-minute crises. You're not going to be stressed. Believe me, it's a great feeling to walk into school the first day of class and KNOW that you're going to get an A in all of your classes.
Since you're going to spend your study time efficiently, and you're not going to be stressed, you can actually enjoy activities outside of class.
So try it out. Amaze yourself, impress your friends, make your teachers happy, and show your parents that they have given birth to a scholar.