you can take a test after you study, this will help in letting you know what you have to learn and what you have learned.
yes you can revise again and again so that you can retain what you have learned
when we mug up things without understanding it becomes very difficult for our brain to process it. Try to understand the concept and make it as simple as possible before jumping to some next concept.
Try to understand the concept rather than just memorising everything. You can also do one thing that you can learn and then write the thing that you have learnt in a notebook (without seeing) this way you can figure out what you have forgot and can point out the mistake. This way your hand writing and spelling ls can also improve.