Monsters vs Aliens

I recommend doing this on the first B.O.B. turret sequence, which is a short while after starting part 3 of Chapter 1, which is the first time in the game where you control B.O.B.

I recommend doing this achievement as soon as you've picked up the following achievement: Once you've got this achievement, focus on spitting down the main helicopter, which is distracting Insectasaurus with a pair of spotlights. When the little helicopters (the ones that are facing B.O.B.) fire missiles, you have a choice, where you can either use your shield (LT) to protect yourself, or you can get 50 points for each missile you shoot down, and 100 points for each little helicopter you shoot down. Either way, it's a very easy achievement, as long as you watch what the little helicopters are doing, and don't focus solely on killing the big helicopter.

One of the easiest places to do this is the first turret sequence B.O.B. goes through in Chapter 1. Concentrate on the main helicopter with the hypno-light but make sure to destroy all of the other copters as soon as they appear. Remember, you can also destroy missiles so try only using the shield if they come too close to you. As long as you don't lose energy, you'll get the achievement once the sequence is over.