Break them down, step by step. You should try to understand the reason for everything happening, rather than just the fact that it does happen. This way you can make sense of what you're learning while also being able to apply the reasoning to other mechanisms. Not only does it make remembering what happens easier, but it also can help if your recall fails you - the point of being able to understanding each process means that you can predict or make an educated guess at what is likely to happen.