Choose the game
Start with a playthrough you are switching in and out of. Checkpoint shines when there is distance between one session and the next.
Save the context
Write where you are, what the objective was, and any important clue. Two useful lines are better than a long note you never read again.
Leave one next action
End with something concrete: talk to an NPC, return to an area, improve gear, or review a quest. That detail makes coming back easy.