Remove the knotty pine cabinets from the wall. Take them apart. If they're secured by nails or are difficult to take apart, just remove the doors and any fixtures.
Sand all surfaces of your cabinets with a medium-grade sandpaper. You should avoid using an electrical sander, as knotty pine is very soft and easily damaged.
Finish with a fine-grit sandpaper.
Wipe down the surface of the cabines to remove dirt and sand debris.
Apply a coat of wood primer to your cabinet. If the manufacturer of your primer recommends a second coat, apply another once your first coat has died. If you're planning to apply a clear varnish to your cabinet, make sure the primer you use is transparent.
Allow the primer to dry completely. Apply a coat of paint in your desired finish. You can use a varnish or paint of your choice. If you want to disguise the knots in the pine, use a dark varnish or paint.
Clean the cabinet fixtures with an appropriate metal cleaner. You can buy cleaners for metals like copper and silver from hardware stores or online.
Polish your cleaned cabinet fixtures with a metal polish.
Reassemble the cabinet and remount it on the wall.