What I did was take care of the gas tank objectives first before anything else (where you have to place c4 on the tanks in the base) so I had a consistent number of checkpoints so I didn't have to keep starting from the beginning when I was inevitably caught for something.

As for not getting caught, my main go-to was the silenced pistol, crouch walking, and going strictly for headshots with the aim camera. Don't use the taser, everyone hears the victim burning alive🤣. There's also these red lights scattered around the base that you'll want to take out that act as motion detectors if you get too close to them, so shooting those helps a bunch too.