Plan ahead to give yourself enough time to study. It is very important to give your brain enough time to absorb the material you are learning. You may have to make several attempts before understanding more challenging concepts. And all subjects, from the simple to the complex, will have to be reviewed to ensure you do not forget what you have learned. Have an idea of the kind of pace you need to keep up and come up with target time frames.
Rewrite things in your own words. It is easier to understand and remember concepts that are phrased in language that is natural to you. Rewrite important facts and create an outline. The outline will also help you organize the subject you're studying in an organizational method that is suited to your understanding. For example, your textbook may write a chapter in a chronological order while you remember things more easily if arranged by theme. The act of writing will also help you commit facts to memory.
Break subjects down into sections. As you work through a subject, study one or two new things at a time. After you are sure you have thoroughly understood a subject, then practice before moving on. This is very important for subjects like math, which continuously build upon previous knowledge. It is also important for subjects with concepts that do not necessarily depend on each other, simply because it is easier to learn things a little at a time instead of trying to retain large amounts of information.
Study when you are alert. It is hard to understand and retain information when you are lacking sleep or mentally exhausted. Plan your study sessions for the time of day when you are most alert, and you will find it easier to concentrate. Limit distractions like television and instant messaging. Many people find music conducive to study, as long as it's music they are familiar with - your brain will pay more attention to new music, which will compete for your attention as you study.