October Novel Prep Challenge

First off, and this is probably obvious, but what we're doing in the October NaNoWriMo Prep Challenge be pre-writing for NaNoWriMo itself? Or is that up to the group members?

Also, if any previous participators in NaNoWriMo would like to inform me of what to expect or tell me some things they wished they had knew the first time participating, I would greatly appreciate it.

Sincerely,
Rachael