Crimson Heads

Ahh, Crimson Heads, how I hate thee. I swear to god the designers made these bastards just to piss the hell out of Resident Evil veterans. Oh, and scare the living shit out of those of us who started the Resident Evil series with this game...such as myself. Anywho, the long and short of it is when you kill a zombie...it doesn't stay dead. I know, you went to all that work, wasting bullets that you need to save to keep yourself alive...and the fuckers get back up. Well stop whining, bitch, I'm here to save the day.

Crimson heads are obscenely dangerous. Not only are they usually faster than your main character but they do at least double the damage and take almost triple the ammo to kill. Oh, and they can also decapitate you if you're at around half health so try to avoid them.
Crimson heads are far more dangerous to Chris than Jill. As Jill you get very large, explosive weapons and at times enough ammo to blow a chunk off the planet. On the flipside to that the strongest weapon Chris' has for 85% of the game are the shotguns. Which doesn't make for a fun time when fighting Crimson Heads...'cause they can take about 6 shotgun blasts to the face. Fun, eh?

Ok, here's where the programmers decided to save the day. There are two ways to keep the zombies from getting back up:
Decapitation is the first. To decapitate let the zombies get close to you and then take the shotgun aim upwards at the zombie's face. If you're lucky this'll blow the damn thing's head off. The second means of decapitation is to blow the zombie's legs out and then when it grabs your leg to step on it's head. Both means of decapitation are luck of the draw as the gun doesn't always work and the head steppage doesn't always crush the head completely. Decapitation is preferrable but not as reliable as the second preventitive measure. There's a third way thats 100% reliable and only available to Chris. Equip the flash grenade defense item and let a few zombies gather around and let one chomp you. Shoot the zombie that bit you in the face and the flash grenade'll blow up. Effortlessly decapitating at least the zombie with the grenade shoved in it's mouth.
The second action to be taken is the burn the body. This can be achieved in one of two ways: the first is to use the kerosene combined with the lighter. You'll find the kerosene tanks strewn about the mansion and the fuel canteen to hold the kerosene in the Eastern Stairs Save Room, the lighter is found nearby on the next floor. The fuel canteen can hold two hits of kerosene which, obviously, toasts two zombies. Each kerosene tank holds only five shots of kerosene. So be careful with it, try to pile up the bodies if you can get them to die on the same spot so you can burn multiple zombies with one use. Within the mansion itself there are around three tanks of kerosene so you have enough to kill fifteen zombies which should easily cover the number of zombies you encounter in the areas you'll be commonly using. On easy, at least, on normal and hard you have to really try to pile them up or outright avoid the zombies. 'Cause if you don't kill 'em they don't revive.
The final way to kill zombies dead in one go is unique to Jill. Using her grenade launcher loaded with incindiary rounds you can light zombies on fire upon attacking them. Unfortunately incindiary rounds are limited...unless you want to cheat. Check the secrets section for a grenade ammo multiplying glitch.

Ok, here's the most important part of this section: revival times. Revival times differ depending on the difficulting level.

Finally, the kerosene tank locations. There's one in the garden where you get the herbicide, one in the eastern save room, one in the broken shotgun room, one in the shack out back of the mansion(if you can't find it, it's where you encounter a certain... enemy thats unkillable...), there's one in the save room of the residence outback of the mansion and lastly in the underground lab. One final note is that when you reach the underground lab you're nearly finished the game. And due to this the programmers decided to be cruel and make it so the zombies revive in about 5 minutes or less. As Crimson Heads, so kerosene is a must. Well, thats all for this crap, folks.