Ask at least one question in every class.
Asking questions is a simple and effective way of ensuring you will pay attention in class. Take this one seriously and you cant help but learn a few things that otherwise would have passed you over. No matter how dry the teacher's teaching style may be asking questions will increase your level of interest. Why? Because in order to ask a serious question you have to be paying attention; make it your goal to ask at least one well thought out question about something the teacher has said in the lecture and without even trying you'll find you retain more information in general. Turn it in to a game by trying to ask a question that will challenge your teacher to do some thinking of their own in order to give you an answer.
Don't be afraid to answer questions, even if you're not sure of the answer.
The number one reason people don't answer questions in class is not that they don't know the answer, it's that they fear looking stupid in front of their peers. More often than not you know the answer but don't realize it because you're not 100% sure that you are right. Rather than risk looking like a dolt you keep quiet. 16th President of the United States Abraham Lincoln once said, "better to remain silent and be thought a fool than to speak out and remove all doubt" and this may be good advice for a politician but for a student it is among the worst things you can do. Believe it or not being wrong adds to learning by reinforcing the correct answer in your mind and being right acts in the same way by giving you confidence in the things you think you know. So speak up and try to answer at least one question each class.
If you're painfully shy get the benefits of the ask/answer questions strategies with a few simple changes to your note taking habits.
**In fact, this is a good note taking strategy for ALL students.
If you are really afraid of being thought a fool or are simply shy about talking out in class there is another strategy you can employ to take advantage of the ask/answer questions learning technique. As part of your note taking routine write down all the questions your teacher asks and the correct answers that are given and make a notation on who gave the answer (a students name or the teacher for example). Make note of all the questions that are asked by other students in a similar fashion; with the question, correct answer and name of the student who asked clearly marked down. Put the asked and answered questions in double brackets ((like this)) so you will later know that they occurred outside the normal course of the lecture. Also, make a notation of questions that nobody seems able to answer as teachers often use these questions on exams. Finally, when you have a question you wanted to ask write it down and mark it with an asterix* or some other symbol. Later you can ask the teacher the question in private and immediately write down the answer they give you or look up the answer yourself. Later when it comes time to study for an exam look through the names of the people who seem to often answer the questions correctly and try to study with them. Make a list of possible exam questions based on all questions asked in class and put them on flash cards to quiz yourself.
Read your notes each night before you go to bed.
That's right, read your daily notes each night in bed before you go to sleep. Treat them like a novel you are really in to and make it a habit to read your notes at the end of each day. Even if you're reading a book at night for pleasure (which is very good) while in school make sure the last thing you read each night are your school notes. It is a proven fact that events and information that you are exposed to in the last hour prior to going sleep will stay embedded in your memory. Think about it, you can almost always answer the question "what did you do before you went to sleep last night?" with little or no effort while other daily details are not as easy to retrieve. The reason for this post slumber retention effect is still being studied but whether science understand it or not it will help you retain the information from your lectures if you review the notes daily and by doing it right before bed you have the added benefit of this strange psychological phenomenon.
Employ these strategies along with good note taking habits and a genuine desire to do better and you will see improvement. Good luck and happy grade boosting!