Wooden drawers with wooden drawer slides often become sticky and difficult to open and close. Moisture is usually the culprit, making the wood swell or warp slightly and causing too much friction between the wood of the drawer and the wood of the slides. A sticky drawer can be very frustrating, especially if you use it frequently.
Try this quick fix: Rub a block of Gulf Wax along the wooden drawer slides and along any other high-friction points on the drawers. Gulf Wax is a household paraffin wax, commonly used for canning and making candles. The gulf wax will lubricate the moving parts and make the drawers operate much more smoothly.