Master the Knife in Resident Evil

So, just ran out or are running low on ammo, or just want a challenge? Get out the good 'ole knife and start slashing away at zombies!

Steps

Practice using the Make a Knife out of Scrap Metal on zombies. You will not be able to do enough slashes in a row to kill it without being grabbed. So instead, slash it once or twice and then run away or run behind it and start slashing.
Get good at dodging zombies. This is another important skill. At full health in narrow hallways and corridors, try to get past a zombie without being grabbed or using a weapon. The best thing to do is approach it, and step back or to the side when it lurches toward you. It won't be able to move again for a second or two.
Practice on harder enemies and bosses. Dogs would be the next step. Then, bigger things, like Hunters, Lickers and bosses. Yes, almost on all the bosses you can use a gun or either a knife. Most bosses are big and slow.

When a zombie falls down but is not dead, take advantage of your chance before it gets back up!
Don't be surprised if you get grabbed. Always carry healing items, and for Resident Evil remake, defense items. In some games, you can wiggle the control stick when grabbed to make them let go of you. Jill can also dodge zombies in Resident Evil 3.
If you are using the knife only because you are running low on ammo but still have some ammo, alternate between using the gun and knife. Shoot it a few times, and slash it when it is on the ground.
If you can't see the zombies on screen when you enter a new room, listen! Often you will be able to hear footsteps, moaning or crawling.
In Resident Evil 1, always play as Chris instead of Jill. He is faster, has more health and also better with the knife.

It takes time to master the knife, and you may die often while learning this. Don't get discouraged. Keep practicing and eventually you will master this process.