Credit for this video goes to AchievementHunter. On the video it also shows you how to get Gesundheit! and Oh No You Don't if you need those also. But for Light My Fire which starts at 2:18, make sure you have a couple Molotov's and meat bait also helps, though they didn't use any themselves.
EDIT: The Meat Bait is a mod that you get from Mother Helen after the "Drop By Drop" which is one of the main quests. You need 3 meat and 1 duct tape for it. And its regular meat you need, not floater or suicider. To get meat you have to smash a zombies head, so you will need a blunt weapon.
EDIT: Credit to DarknessCalling - If you aim a shotgun at a zombies head and manage to blow it off you can usually you can find meat near the body.