Every month check that all threaded fasteners are secure, paying careful attention to brakes, handlebars, racks and cranks. Make minor adjustments if necessary. Check that the brake blocks are not overly worn, hit the rim squarely and do not rub the tyre side walls when fully applied. Also spin the wheels to ensure that the blocks are not dragging on the rim at any point. This may be caused by a buckled rim.
Cables usually break near the levers so pay particular attention there.
The jockey wheels may occasionally need removal and thorough cleaning, many do not need lubrication and those that do should be lubed with a dry lube such as graphite, paraffin or a synthetic lube. Your chain lubricant should penetrate the rollers to ensure the chain works efficiently but no wet lube should remain on the outer surface of the chain as this will attract grit. Remove and soak the chain in solvent then dry and lubricate it if it becomes very grimy. A well cared for chain will only need a wipe over and careful lubrication ensuring that the excess lubricant is wiped of all external surfaces. Modern dry chain lubricant greatly extend the chain life.