First of all, get out your knife (see caption 'A') now go to pause menu, options, keyboard settings and then select secondary weapon function (sniper zoom and secondary knife attack). Bind any key as the secondary weapon function and now your ready.
I find that it's always best to approach someone from behind when you want to knife them. Now this may sound pretty obvious. But if you use the secondary weapon function key you bound earlier, you can kill them in one hit from behind. Not bad huh? To do this aim at the small of their back or their neck.
However if you want to knife them head-on you need some more tips. When you are going to knife them, press your fire button and the secondary weapon function straight afterwords. This creates a fast and powerful knife combo that if performed correctly will have excellent results.
Thanks for reading this Tutorial, there are more coming soon! Also thanks to all of the people I knifed to find these class knifing techniques!