How to Kill a Witch Effectively

This guide will teach players the 3 main methods of killing a witch in Left 4 Dead

Fire Method

Molotovs and gas cans are effective against witches, as long as you can keep the distance between the witch (it takes around 15 seconds for a witch to die by fire, even less if your teammates protect you). Basically, just burn the witch if you got no shotgun (assuming you HAVE to kill her to get through a path).

Shoving

Since there is no shove cooldown in L4D1, you can pretty much just keep her stumbling in an infinite loop while someone else guns her down. It's a pretty good tactic but be careful.
(I couldn't find a L4D1 video but you can just watch how this witch gets absolutely bullied)

Shotgun Method

Lastly we have the best method in my book, the shotgun method.

Firstly, you want either of these two weapons, preferably the Auto Shotgun in case you miss some of the pellets on the first shot:
Pump Shotgun:
Auto Shotgun:

Alright, so first off: The Pump Shotgun IS good for killing witches, don't get discouraged to use it just because I said Auto Shotgun is better. It's great if it's all you have, but the thing is, you have to hit ABSOLUTELY every pellet, otherwise the firing speed will make you vulnerable. This is why I prefer the Auto Shotgun, due to the faster firing speed.

Just use whichever one you prefer. Just make sure you hit your shots.