I understand the the L1 button is the "sneak button" and that you sneak up behind them extremely slow, but I can't seem to pull off the sneak attack without alerting them first, even in the very first mission.
When I try to sneak up behind the first guy (using L1) that comes out of the door (urinating next to the tree), I try to use the anesthetics and right before I get into range to attack him he starts turning around and my alert box starts flashing red, even though I complete the attack successfully in the end. I suppose that one doesn't matter as much since there's no one around, but I assume if I did it correctly the alert box wouldn't flash. However, when I try to sneak up behind The Don (again, using L1) with my Fiber Wire, he always turns around and becomes alerted before I can actually strangle him, then after I strangle him his guards barge into the room.
What am I doing wrong with my sneak attacks? They don't seem to be very sneaky if they can get an alert off before you actually get to them... I've tried doing this several times and he is consistently alerted each time. I'm supposedly able to do this without alerting either of them, but I'm obviously missing something.