That seems like a fairly good tactic there, OP, if I'd been killed by a sniper as efficient as you say you are, I wouldn't complain, I'd give him a little credits for his skills.
I don't play MW2, but I do ply CoD4 all the time and have perfected some tactics for each level:
Levels: Backlot, Downpour, Countdown and Strike
Weapons: M40A3 Sniper Rifle and Desert Eagle
Perks: Frag x3, Stopping Power and Dead Silence
Tactics: Never stand in one spot for too long, change between places every three kills.
Levels: Pipeline and Bloc
Weapons: M40A3 Sniper Rifle and Desert Eagle [SUB]Sometimes a silenced USP .45[/SUB]
Perks: Bandolier or Claymore x2, Stopping Power and Iron Lungs
Tactics: Stay on the edges of the map, snipe every enemy, if seen, change places, quickly.
Levels: Vacant and Wet Work
Weapons: Silenced MP5 and Desert Eagle/M14 with ACOG Scope and Desert Eagle
Perks: Frag x3, Stopping Power and Martyrdom [SUB]People may hate me for my Martyrdom.[/SUB]
Tactics: Stay on the outskirts of the map, never go into the middle, kill everyone that goes on the outskirts (Exhausting during TDM on Wet Work)