Well as i heard from FJ saying that American people are very good at COD4 at PSN...well I was using a few tricks on them...

And i noticed many of them group up in ONE house full of snipers and machine gunners..especially on Overgrown and Creek...I used this tactic

Ghost
Ak47 silenced
m1911 USP .45 silenced
smoke grenade
bomb squad
UAV jammer
dead silence / steady aim

and I noticed these americans pay attention to the radar MORE than they pay attention to the screen itself and I passed by like 3 guys and they DIDNT even notice me and I was like getting more than 7 killstreaks in that house itself...how? I just prone and hide in the dead bodies i killed and yes since your in hiding theres gonna be like a 2 or 3 second delay from my enemies cos they had a little trouble in their brain asking themself " is that what i think it is? ) then I hit in the face and the other guys in the other rooms cant hear me as they're busy sniping and focusing themself to shoot the others i would shoot them too.

and the bomb squad WORKS WELL against claymores along the way and yes and being a GHOST on COD4 is now my favourite class