Knowing how to use a grease gun is essential to maintaining your machinery and prolonging the life of your equipment. Start by loading the grease gun with the appropriate type of grease. If using a cartridge, remove the cover and secure it. Pull the trigger until grease is visible on the butt end and prepare the gun. Clean grease fittings on machines to prevent contamination. Attach the tip of the grease gun to the fitting securely, then gently squeeze the trigger, applying grease until it oozes from the fitting or seal. Finally, disassemble the gun. Clean the tip and stored appropriately for future use.