The environment in which you study is important only in that it is a small part of the environment in which you learn. All learning is not done with study, which is why some people never study and receive good grades and others study diligently and can receive mediocre grades. Some people have been successful at determining how they learn and others have not.
Learning does not happen solely by will. Because you prepare a time and space to absorb the material does not mean that you will necessarily learn optimally. Learning is a constant process and you could be fixing yourself a bowl of cereal in the morning before class and suddenly an idea comes to you, or brushing your teeth at night and you finally remember who sang that song you were thinking about all day.
Stay relaxed. If you begin to feel frustrated then your ability to learn will suffer. Take a break. Call a friend. Go to a movie. A persons mind is active 24 hours a day. Just like the body needs nutrients from several sources, so does your mind. It will absorb best what it needs, which is not necessarily what one might desire at the time. (I'm sure there is a lesson about cooperating with the id in here, which is a lesson that people tend to learn somewhere around middle age. Know thyself.)
People do not think in a social vacuum. The beliefs and attitudes of those around a person will affect the way in which they learn. Your prescence in a classroom affects everyone in that class, including the teacher and the way she teaches. For example in one of my classes there is this guy that is rather annoying. He taps on the desk and shakes his foot and makes excuses for late work and says things like "Can we end class early today because I have to pick someone up." His attitude towards the class is disrespectful to everyone in it. The entire class is reduced in potential because of this person. One person is not separate from the people around them. To increase your ability to learn increase the potential of those around you. (This is why I suggested friendly competition earlier.) You probably have an idea of who in the class will be receptive to this. For a particularly difficult class start a study group where you can do homework together. You will find that if you are trying to explain the concepts you will learn them yourself much, much better.
Find another goal than getting a good grade. Getting a good grade and learning the material are completely different things. I'm sure there is a strong correlation but they are still seperate. The material itself is most important. If your worried about your grade you are wasting time and energy that could better be used focusing on your next lesson. Don't let a bad grade on a test disenhearten you or discourage you. You are far more important than any test you could ever take. You are better than that test and that grade does not encompass you. Don't use this as an excuse not to try, but be hopeful and courageous and step up the game for the next test. Your self-image is important to your learning.
Get everything going right and you will be not only a well-oiled thinking machine, but you will have tools to deal with any situation in your life and you will have helped many people better themselves along the way. It is about more than just pure knowledge, which can't make you happy. It's about finding a greater understanding of the world and your place in it. That is true learning.
What was the question?
Huck