Empty and clean the cupboards if necessary. If the cupboards are old and need new paint, they might need cleaning and emptying. If they are new cupboards, cleaning and emptying are not necessary.
Sand the cupboards with a fine grit sandpaper. Select a sandpaper that is about 400 grit for the best sanding results. Sand along the direction of the wood grain until the pine is smooth to the touch. Brush off the wood dust or blow on it to remove the wood dust. Wipe down with a soft cloth to remove all remaining dust residue.
Apply a coat of primer to the wood. Pine wood can have knots which bleed through the paint, so a wood primer is painted on the pine. When applying to the wood, stir the primer with a paintbrush and remove the paintbrush from the paint. Wipe the brush along the side of the primer can to remove excess and dripping primer and then use firm, long strokes along the grain of the pine wood. Cover the cupboards with primer. Allow the primer to dry. Follow the primer directions for exact methods and the number of coats.
Paint the cupboards in the preferred color. Painting is similar to priming. Stir the paint and wipe excess off the brush. Paint in long, even strokes along the wood grain. Allow the paint to dry. Add a second coat of paint as preferred or according to the paint directions.