A study plan makes life so much easier. Without a study plan your just winging it and trust me you will leave topics out. Once you see what you have to do written out it will give you the motivation you need to start studying.
Step 1 :
Write down all topics for each class.
Write out a calendar with exactly how many days you have left.
Lets say you have 60 topics to cover and 30 days left before your exam. That means you have two topics to cover each day. These two topics should be from two different subjects and ideally one hard and one easy topic.
Step 4 :
Try to study harder material first. This way you can go over these again at the end. Its much harder to study hard material closer to exams because you will be stressed.
Step 5 :
Highlight each topic you finish. This way you can see how much you have covered already.