Turn off the water supply under the sink
Open the faucet to release any remaining water
Plug the drain to prevent losing small parts
Remove the faucet handle
Take out the cartridge, stem, or valve assembly
Inspect O-rings, washers, seals, and gaskets for wear or damage
Replace any damaged parts with matching replacements
Clean mineral buildup from internal parts and faucet components
Reassemble the faucet
Turn the water supply back on
Test the faucet for leaks
Tighten connections if needed
Replace the entire faucet if repairs do not stop the leak