I DMed eight players in a campaign that lasted a year. Here's my advice, as you asked.
At the outset, convince your players that everyone minding their game etiquette is a serious boon to the game, more so with a large number of players. The contrary is also true.
Ask them to keep out-of-turn conversation quiet and to a minimum. Having four people asking you to repeat yourself four times in quick succession will do nothing for anyone's enjoyment.
Ask them to refrain from all OT conversation, except during breaks.
Ask them to make any rule challenges or queries that they feel compelled to make during play brief and, if possible, accompanied by page references. Ask them to accept all your rulings during the session, for the sake of the session. Reassure them that you want them to bring all grievances to you out of game, that you will give them lengthy and careful consideration between games, and that you will fix or compensate for any errors you find that you have made in subsequent games.
The size of the group is going to mean that while encounters may not necessarily take longer to play, the time between player turns will be longer than usual. Remind players of this and advise them to pay as much attention as possible to what other players are doing. Tell them that you expect them to be ready to tell you what they want to do when their turn arrives (after dealing with any reasonable questions the player may have before deciding his PC's precise course of action).
Use a battle map, grid, miniatures or something visual. Snacks work as counters. They hold people's attention, save space, taste good...
Use initiative cards, even if you're going for one encounter per session.
Keep copies of all the PC character sheets but, if you can, also try to get all the PC data onto a single sheet (I managed to do this on two sides of A4 in six point for my party of eight). It often helps to have a single handy table containing all the party members' abilities.
Encourage the players to leave their PCs' character sheets and notes with you. (You don't want to have to give a player your copy of an absent player's character sheet.

) That way, when players can't make it, their characters can be played by their buddies who are there. This worked splendidly for my group. Everyone trusted each other and the rogue's schizoid tendencies only added to the flavour of the character...
Enlist willing players as DM assistants at every opportunity.
Tell them they should be very, very nice to you, always.