What I do is ensure all mating surfaces are clean and bright. Then I use Caige
Laboratories contact cleaner ($15 a can but it goes a long way). I use
"Stuff", and yes that is the name, teflon based insulating grease to coat the
surfaces and fill the voids; exess is wiped off. Then I use a bead of silicon
rubber to seal all joints, coax entry points into connectors, etc. After it
cures, I wrap the entire connection with Scotch or 3M black electrical tape,
2-3 wraps. Then I again use silicon rubber to completely coat the entire
assembly from end to end, sometimes with 2-3 coats. After all that cures, I
use CoaxSeal on top of that. I've had connectors last 10+ years that way, not
sure how much longer they would have lasted since I took the antennas down when
I moved.

Evan