I finally got all 69 stars in Modern Warfare 2's 'Special Ops' mode, after many frustrating hours of attempts. Two missions kept pissing me off. Then I found this video for one of them (Terminal):
It totally worked! After about seven or eight tries, I nailed it no problem. I was trying to use a riot shield and 'turtle' up in a corner whenever I was about to die. As it turns out, that was the wrong approach.
Now about that other mission, Wetwork:
Looks easy, doesn't it? He completes it twice in under five minutes. Yet, it took about five hours for me to replicate. Five painfully frustrating hours. Shotgunning guys on the first staircase NEVER worked out that easily, because the accuracy on it is terrible, and usually they just fall to the ground in 'last stand' and fire a pistol at you (and block the staircase, since you can only step over dead bodies). If your timing and placement with flashbangs is off by half a second, or if your aim with the AT4 launcher is off by a foot, you'll get killed and have to start over. But, when I finally finished the mission, I stood up, and said, 'IT IS ACCOMPLISHED!'