ok this is probably a really noob question but bear with me, i want to start mounting a few things around my truck but my biggest fear is once i start drilling these holes i'm going to start getting rust like crazy, i live in Canada so we have alot of snow and alot of salt, so does anyone know how to properly drill and protect these holes from corrosion.

 

Just repaint the bare metal with either the body color (if on body), or POR-15.

 

mark your hole, lay down masking tape to protect surrounding paint and to help with chipping away the paint at the hole.

 

POR-15 is great. Just make sure any cutting fluid you might have used or oily film is removed from the area with degreaser first.

 

put tape on where ur cutting (so its already on the line) then ad some more to protect from overspray then hit it up with some RUST paint like Rustoleum (sp?) or POR 15

 

Center punch the area.

SLOW drill speed.

High Quality masking tape.

 

POR-15 is for rusted metal unless you treat the metal first with an oxidation agent.
IMHO
Do the masking tape thing for sure.
Finish up the hole.
Get some DuPont Etching Primer, spray the bare metal area, get underneath if you can if not use a Q-tip and spray it then wipe it on the inside as best you can through the hole. Most rust starts on the inside.
Paint with a good DuPont Automotive Paint.

 

If the area is covered just use a dab of silicone.
Like others said, paint exposed areas.