How to get a 7 killstreak easily playing CoD MW2?

I've been playing for 2 month and it's really hard to get a 7 killstreak.. So far I've got 3 times nuke and 14 chpper gunner,but only when I'm camping and I don't feel like I'm in the game because I'm just waiting for someone to show up.. Any tip to become a good run and gun??? I use ACR and M21 EBR and sometimes MP5K---- avdijk88