I am running Pathfinder now. I print out every monster I'm going to use and highlight stuff I want to remember. It really helps.3rd edition and it's legacies trained me to print out B&W pages of monster stats for any adventure because of the little abilities and defenses that were hidden amidst the numbers, skills and the like. I then go through each stat block with my handy-dandy rainbow set of highlighter pens and (using no particular color, just a different one for each) mark each ability or defense I feel needs to catch my eye at the table.
I was surprised to find this happening sometimes even in 5e, where the stat blocks are SO simple I think sometimes we've been reconditioned to think they're easy to remember. They're not, still need those highlighters!

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.