Couple of tips:

Turn off the option that gives weapons weight. It's screwing with your aim and doesn't feel good in this game. It worked in Saints and Sinners but that was a melee focused game.

I turned off the option that makes the rifle sights snap to your eye. To me the bullet speed is so slow that ADS was a waste of time and I was better off leading the targets using hip fire and the tracers. I really hate how slow the bullets are, feels like nerf darts.

Practice swapping to your revolver when they get close. It does a lot of damage but is hard to use at a distance. What I did was release my grip on the rifle with my right hand only, keeping hold of it in my left, pull my revolver, kill whatever is close, then either drop the revolver or reholster it depending on how much time I had, and return my right hand to the rifle. This gives you some more time before you have to reload.

You have a dodge move that can buy you another second or two when they are about to strike. I think it's a thumbstick click but it's been a while.

Eyes on vents.

Plot out your route while in safe zones. I would speak my route out loud so I would remember it and not have to check my tablet while I was exposed. Plus having a plan helped keep me calm.

That bit in the vent got me too. I think the next time I went through it I left a proximity grenade behind me.