"MVP" stands for Most Valuable Player.
Usually you need to have the top score in the game type. e.g if it was multi flag you need the most captures, in a slayer game, most kills. But remember it must be in a ranked playlist.
The easiest way to do this achievement is to do the playlist where there is just two teams of two against each other. With only one other person and one other team, you just have to beat the other team and do better than your other team mate.
Example: When a team mate quits along with a player on the other team quits as well in a two versus two, and you win against the other single player.
1.Camp, you must do what ever it takes to win. Camp with a shotgun behind walls/shield doors. Keep a Battle Rifle or an Assault Rifle in case they are a bit too far away. Be careful to not get lured past your hiding spot. Althoug be prepared for players to complain.