Which strategy is the most efficient for Clickers?

While Rob Avery's suggestion of avoidance is a valid one, I usually took it as a challenge to kill all of the enemies in an area before moving on, so I needed different tactics. I was also stingy with my shivs so barely ever used them other than as a rarely used emergency escape from clickers (with the skill) or to open doors that required shivs, so stabbing them all in the neck was out for me.

I found arrows to be really effective instead, at least on the unaware clickers. Most of the clickers you face throughout the game are easy to get close to without raising an alert, and it's usually trivial to get close enough to plop an arrow into their face, which is a nice, silent instant-kill. Just save your arrows for this purpose... they're overkill for humans, which you can just strangle, or runners, which are usually easy to melee unless they swarm you (at which point, you aren't going to want to use a bow and arrow anyway). As a bonus, you'll sometimes be able to recover the arrow after the kill.

During those occasional times when the clickers are aware of you and charging endlessly, the shotgun (if you wait until they get very close) or the rifle worked best. On hard, the rifle was often a one-shot kill even if you don't hit the head, and upgrading its ammo capacity was a big help if you needed to take out 2 or 3 in a row.

Lastly, while it costs 75 drugs (or whatever it is you buy skills with), the skill that lets you get a clicker off of you with a shiv can be a really big help. I recommend that if you plan to get it you get it as soon as possible in the game though, because it seemed to me that close-quarters fighting with clickers was a lot more common in the early and mid game than the end game. Given that without the skill a clicker's touch usually means death, it's nice to have on some of the tougher fights, particularly if you're playing on a harder difficulty where ammo is scarce.

Though you have to get close, I like to use a brick as a melee weapon. Using a shiv, pistol/long gun, pipe/plank etc. works, but at the cost of precious supplies. Since bricks are so ubiquitous in the game, it is an option to dispatch the Clickers and preserve those supplies for something else.

I suggest using a brick to stun them and finishing them off with a melee weapon (don't need to upgrade). Prioritize your shivs for the locked doors.

I wouldn't suggest getting the shiv master skill. It's a waste of supplements as it takes up a whole shiv to get the clicker off you. Or you can bait one to a secluded place and two headshots with a pistol will finish the clicker. After the first headshot, they normally just stay still and look down so getting the second headshot wouldn't be much of a problem.

in the first half of the game I mostly threw a bottle and when they all ran to it then id throw a molotov cocktail. in a confined area it easily takes out several at once without giving away your position. but once you get past half way you learn to use the bow more effectively. I used it more than the flamethrower.

I would either use a shiv on them or i would save my shivs for locked doors and use a upgraded melee weapon preferably a pipe or a axe (if you are far enough in the game). you could also use the shorty pistol or a shotgun for close range.

My strategy either use a shiv or a pipe to kill them. Also if runners are in the area take the runners out quietly. Clickers are fairly easy to kill when no runners are around.