New Player

So I'm a new player and I'm finding the stealth in this game to be basically impossible.

I had to fight the two dudes in the training most of the times that I tried it and the few times I managed to not fight the first guy I didn't get the stealth animation so it alerted the second guy.

Can anybody offer some tips or tricks because between the crouch clinging me to the walls when I don't want it to and not being able to move up quickly enough I'm just not sure how you're supposed to do it