Revision is the first round of changes that you'll make to your paper. This is just a first pass is designed to address the organization and structure of the paper, as well as the central ideas.
These techniques can each be done by themselves, in sequence, or all at once, but before you start, it is a good idea to ask yourself this question: Does the project meet the assignment requirements? This does not refer to the page length, or some of the other details, what is mean is:
If the paper does not meet the assignment requirements, start there. Figure out what parts of the assignment are missing and include them. If you are not sure, ask your professor--they are the expert on what they want and are the only person who can truly tell you if you're on the right track.
Outlining a paper that you have already written is super helpful because it acts like a mirror and shows you things you might have missed in the structure or organization of your paper. The outline can be as brief or as detailed as you want, depending on how long your paper is and how much of the paper you already have written.
To outline a paper you have already started writing, read each paragraph and write down the topic of the paragraph in the outline.
The outline will show you which ideas you actually write about, and can indicate where there is something missing. The missing information might be a key part of the paper, or a hole in the logic of the argument - do you talk about A and C, but never discuss B?
It can also be helpful to note how many sentences you spend on each topic or how many sentences long each paragraph is - that will tell you which ideas are much more fully developed (not to mention which ones you clearly have more to say about!). If a particular topic is much longer than everything else, it might be worth cutting some of the material for that topic so it better matches the length of the other parts of the paper, or narrowing the focus of the paper to just that topic and expanding it further.
On the other side, if any area is significantly shorter than the other parts of the paper, you'll be able to identify it and then decide if you want to expand it further or cut it out of the paper completely.
Highlighting can be used in tons of different ways when revising your paper.
If you're not in a hurry and have print pages to spare, this is a super fun activity (or if the paper is a huge organizational mess and you're about ready to give up!) - it is more fun if you and a friend do it together. You can do this for each other's papers and compare the result with the original document - it can be very revealing!