acSlater.com on quickly leveling in Modern Warfare 3:
The other way I’ve gotten a lot of points is by using only a UAV and Ballistic Vests. This allows you to cycle through each of them a little quicker and put down more vests for people to pick up.
I had been working on a leveling up guide a while ago but never finished it. Equipping just UAV and Ballistic Vest is definitely the fastest way to get point from point streaks. I also agree that Domination is the best mode for leveling up.
The only other recommendation I would make, relates to challenges. Getting to 75 kills with most guns isn’t all that hard, especially in Domination. Also, some of the perks are pretty easily to complete challenges for, especially things like Scavenger, Sleight of Hand, Overkill and Stalker. Find challenges that are easy that are not hard to go out of your way to complete and do those for some easy XP.