I really agree with Ezekiel. Even when going for reds aggressively, your only chance is to get a huge group of one color and use the special ability to turn them into red souls.
The dogs do more damage than a normal zombie and take less hits. Shoot them before anything else, don't listen to splan. Also, the best weapon is the compound bow, found in Aspenwood. Give the machine guns, shotgun, and hunting rifle to survivors you find and things get a whole lot easier!
I really wanted to get these badges but I just can't tolerate this game any more. It's ugly, it's slow, it's boring, and has no depth of strategy. 1/5, will never play again.