Winter roads throw up diesel, oil and stuff onto the rims. Scrub them with warm detergent and that should remove the worst. Scrub the pads too. Disc brakes need to be finished off with a solvent wipe (eg alcohol) but I've never done that with rim brakes. Rim pads are also less vulnerable to contamination than discs.
If you want to lube your brakes, use a drop of bike oil (eg Finish Line) on the pivot and drizzel a drop along the cable at the noodle.
Occasionally I rescue a rusty bike by spraying WD40. I use bits of card to protect the rim and brakes.