How do i NOT die so much in MW2(Modern Warfare 2)?

In Modern Warfare 2 my preffered Sniper:Intervention (&Occasionally the M21)
Preffered Assault rifle: Tar-21
Preffered LMG: MG4
Preffered SMG:Ump45
Preffered Secondary(s): M93 Akimbo, Spas-12, And RPG-t7 x2
Preffered Perks are SOH pro(Only when using an LMG or sniper) And Scavenger Pro
Preffered map:Terminal
With the Tar 21 I can Rack up lots of kills and i never hard scope with a sniper (to me its nasty)
But the thing is i die to much. It’s difficult to keep up a killstreak…Are there any tips you guys can give me.

p.s. I have tried camping but i get anxious and bored and end up leaving…Then shortly after dying -_-. What are some tips on Camping and some good spots in certain maps.