Didn't take the time to read past first 4-5 responses, sorry if this is duplicate suggestions.
Don't be a rule nazi, but pick a few important ones for the new folks to know ahead of time.
A particular gripe of mine is people not being clear up front whether cash plays. Think of it like this:
Scenario. You've got the nuts on the river. You're against one opponent. They have $30 in chips and a $20 bill next to their stack. You say 'All in' and shove in $60. They say 'Call'. You show the winning hand. They slide you $30 of chips but not the $20 because they hadn't decided if they wanted to commit it to their stack. It's up to you as the host, but I personally always go with the rule 'Only chips play. Table stakes. No going into your wallet for more cash in the middle of a hand.' Whatever you decide, announce it up front.
Another tip - I like to cash out starting with the largest stacks and working my way down. A (very intelligent) buddy of mine recommended this a long time ago; I believe it was based on the theory that if someone is going to get screwed by a clerical error resulting in too little money in the bank, you want the folks that get screwed to be the ones entitled to the least money in the first place (because they had the smallest stacks). Or something like that - my description is probably flawed.
Another big pet peeve of mine - players making change from the big or small blinds, and players splashing the pot. While you don't want to be a rule nazi, try to remind players at the start of the night to let the dealer do all the change-making and to keep bets in front of them.
I like what someone said - rotate the deal including the new players - they need to learn to follow the action.
Good luck on keeping the game going in the future!