Well, the most important thing to keep in mind when you face a huge assignment is to structure your time properly. The thing is that a lot depends on your ability to start researching on time as well as to get down to the actual writing process right after that.
Apart from that, it is also important to have a clear plan of what you are supposed to do first as you need to have some sort of idea in terms of which assignments are more significant and which can be completed later. For instance, you should allocate some time during the day to study at the library.
Besides, it has also proven to be useful to take notes during lectures as you cannot possibly memorize everything. Yet, you will have some information in front of you which will help you figure out what you have discussed in class a few months ago. Improving your study skills is a continuous process. Yet, what is great is that you will get better at it with time.