My advice won't necessarily be good for a competitive score, but here is what I've found from running a school Club station during Sweepstakes.
The main thing is to have fun! Don't take it too seriously if it's your (or anyone that's operating) first time contesting.
For running multi op, it really depends on how many people you have and their experience level and time availability.
If you have people who are completely new, then it usually helps to have two pairs of ears listening with one person operating while the other logs the contacts. Two people at the radio means that there is a double check on the exchange, and that it's easy to swap positions for a break.
That being said, it isn't that hard to log and operate at the same time. I prefer working alone, and use the multi op to avoid spending a whole day in the station.