If your faucet is leaking, start by turning off the water supply to prevent further water waste. Next, try to identify the source of the leak, such as a worn-out washer, O-ring, or valve seat. If you're handy, you can attempt to repair or replace the faulty parts using basic tools. However, if you're unsure or the leak persists, it’s best to contact a professional plumber to ensure the repair is done correctly and to avoid potential water damage.