Best thing I've found for screws in wood is squirt a little epoxy
in the hole when you drive the screw. Not only does it lube and grip better, water
can't work down the threads and into the wood.
Another method is an oversized hole filled with epoxy
. Later drilled for the screw and again lubed with epoxy.
As a shipwright, I've seen boats I worked on come back 20 years later and the screws were still tight and no rot
below. Works really good on lifeline stanchions or anything taking side force.
I use to use Boatlife Caulk, but it's got expensive enough that the tubes sit on the shelf too long. Lately the ones I've bought are half cured in the tube so I've gone to a silicone type product called Lexel. It comes in colors and clear. Has a good stretch like silicone, but is paintable.