I use little note cards. I forget the name of them.. like in a rolladex. Small, lined cards. Easy enough to flick through and catalogue. Different coloured highlighters used across the top line of each card to determine Location, Item, NPC or Plot point.

INDEX CARDS ... index cards. thats it.

Ah, I remember th good ol' days when having some campaign continuity was important... now we're all lucky if we can remember our own character's name, let alone anything about the world around them. fWIW, my Eladrin Warlock is Pae'a'leben, which means "fifteen" in Sindarin. No wonder we have trouble with names...

Here's a suggested template (from the very useful )

Session history
Date:
Players in attendance:
Summary of events:
- Memorable events
- NPCs encountered
- Locations visited
- Creatures encountered
- Treasures discovered
- Exp earned by player
Notes:

To which I'd also add: Notable information/clues