Depends on the size. IMHO parties ~10-20 people are the best. If you go bigger, it gets more complicated and anonymous. Didn't like those very much.

For a run-of-the-mill LAN you don't need much. Make sure there's

* enough chairs

* enough tables

* enough drinks, food

* enough power outlets (know where the fuse is)

* possibility to shade the windows

* somewhere to sit and chat without necessarily gaming

* possible sleeping quarters?

What size? Make sure you've enough room is my first generic piece of advice. Then I'd suggest a list of games people want to play so that everyone is patched and ready to rock.

And Saturday night is pizza night. No exceptions. Rock band/console multiplayer highly encouraged.

We got a vive set up for our last lan (in halifax, UK), it went down well.

People will forget cables (power, network). Get people to bring extra joypads for the people who don't have them for when its time for a game of rocket league...