Okay, I've been playing MW3 for a while now and figured out a way to easily slip through Weapon Levels and regular levels: Specialist Strike Package. If using Hardline, then you could get 250XP for your first kill. Also, when you get all the perks it's 200XP by default per kill. I don't know everyone's skill around here, but my CM901 is at level 20 and my profile level is 42.
So, what do you guys think? Does this help you or are desperate for your regular killstreaks, or Point Streaks? Also, what other ideas do you have to gain XP? Let everyone know in the comments below (oh, a rhyme).