If you're talking about an outline for a paper, you can add in little notes and thoughts that come to you while you're writing it. I know an outline's only supposed to be a rough plan without lots of detail, but if you have a really great idea for your wording or an example to use or something, you can totally add that in. If you're just talking about a study sheet, you can do the same thing: add in little mnemonic devices that help you remember the information. It can be anything. Like, if the reading made you think of something from your own life, write that down, it may help you retain the information.
Obviously, don't waste a lot of time with this, but the formatting can really help. Highlighting the headings and making sure to include enough space for readabilty is important.
I'm not really an expert, but I hope I could help!