Sleep and exercise are big, as mentioned.
There are also various memory tricks. For instance, the people who memorize decks of cards assign each number/suit to something, then develop a scene in their head that goes with the cards. So maybe they see a red banana flying over a purple rainbow, and that would mean the 4 of spades comes after the 6 of hearts... or whatever it may be.
Another thing is changing up locations. Make your locations interesting and novel and you'll be able to recall stuff you learned in various locations. I remember once I listened to an audiobook while on a long walk. When I tried to recall things, I would remember where I was on the walk, and that would remind me what the content was I was trying to remember. It was wild. I find physical books help for that as well. They give context of where you are in the book instead of just a percentage.
Spaced repetition is another thing. Going over the stuff over and over again, over a period of time (days, weeks) helps to lock it in.