A guy named Aftli has just wrote an extensive guide on how to use a Task Killer app on your Android phone for maximum effect.

I have used this guide and my phone works perfectly and I am proud to announce that I have yet to have a lag on my phone since I used this guide. Also my battery has been draining slower than it has been without this guide. (Do note I do not have enough evidence to support the second claim but I will post it ASAP)

Thanks again Aftli for writing this guide and I hope this guide helps other as well.