I'm just about to host my 5th annual quiz at school and points I would make are similar to others...
mix high brow films and reality TV questions in a "screen" round, pop music from all eras, sport across the board...
Put in some questions that are tricky, some that everyone stands a good chance at, and also some that are a complete guess (Guiness World records are good for that)
We also do a picture/famous faces board, a taste test (so far crisps and jelly beans, can't tell you this years in case of lurkers!)
I dot music in throughout. Last year in my geography round we had bits of songs by artists with Geographical connections (Ryan Paris, Berlin, Manhattan Transfer...),
played National Anthems, sporting theme tunes, songs with numbers in them...
The other thing I would echo is to check your facts thoroughly. I always add little notes so if I think someone may argue a fact with me I've got back up (can you tell thats from experience of being wrongish about a James Bond and Star Trek question!)
Above all, laugh a lot. Its supposed to be fun