in every walkthrough, people say "just walk up behind the guard and grab him" but everytime I walk up behind guards, I bump into them or they see and/or hear me before I get a "grab" interaction. What am I doing wrong? thanks.

When you start to walk up to an enemy, some floors may cause more noise than others. As you walk up behind them get as far away from the front of his face as possible. For example, if hes facing left go as far right as possible. To stop him hearing you tap the forward button over and over again and when he turns click the grab button ASAP. Make sure you find out which way he will turn first or you may end up being shot at point blank!!!!

the other thing make shure that ur not moving very fast becaseu just running up behind someone fast doesent realy work

and u dont have to get to close just wait for the action and again make shure that ur noise is minimal use ur noise meter and dont let your footsteps pass the little box otherwise people with turn around

what do you mean dont let him hear you tapping the forward button?how is he gonna hear you tapping something in real life?