Wait for Mr. Anderson to raise the knife then shoot his hand holding the knife.
Mission 2 - Bank Hold-up:
Just blow this guys brains out and splatter it all over the floor.
As simple as that.
Mission 3 - Hostage:
Kill the bad guy, shoot the door twice to unlock and open it, then shoot the hand cuffs.
Mission 4 - Mental:
Shoot and eliminate the three (3) psychos before they shoot the students.
Mission 5 - Magic Dust Bust:
Turn on the N.V. Scope and take out the three (3) bad guys.
Mission 6 - Tagging:
Shoot the cans when the punks are holding up and spraying about.
Mission 7 - Triads:
Turn on the N.V. Scope and shoot the guy hiding in the cafe.
Mission 8 - Chang:
Turn on N.V. Scope and shoot the wall to ricochet the bullet into Changs head.
Mission 9 - Vengeance:
Turn on N.V. Scope and shoot the explosives when the car passes by.
Mission 10 - Skater Pimp?:
Shoot the support under the ramp to break the ramp.
Mission 11 - Youre Kidding:
Turn on N.V. Scope and shoot when the target left the car.
Mission 12 - The 3 Musketeers?:
Blow up the black colored car, then blow up the guy who emerged from the car.
Mission 13 - Nutcase:
Guide the bullet into the psychos head. Careful not to hit the hostage.
Mission 14 - Nu Regime:
Destroy the rocket with the guided bullet first, then blow up the bazooka guy.
Mission 15 - Suicide Bombers:
Two (2) will appear from the bottom right, shoot the C4 pack (aim for their torso) that they are carrying. The one at the top will appear soon after the two (2) at the bottom has been dealt with.
Mission 16 - Mr. Anderson:
Shoot the bad guy holding a pistol as he emerges and attempt to kill Mr. Anderson.
Mission 17 - Convention:
Instead, you shoot the window where the sniper is in once to break it, then shoot nother window, then shoot the sniper again to kill it. After that a suicide bomber will appear, shoot the C4 pack (aim for the torso) to blow him (or her?) up before any real damage can be done.
Mission 18 - Deliverance:
Aim approximately to the left side of the target and the wind will sort of blow and guide the bullet onto the target, causing him to die in a most unpleasant manner.