Turn off the water supply to the faucet
Plug the sink drain
Remove the faucet handle
Take out the packing nut or retaining screw
Inspect the washer, O-ring, cartridge, or valve seat
Replace any worn or damaged parts
Clean mineral buildup from parts and surfaces
Reassemble the faucet
Turn the water supply back on
Test the faucet for leaks
Tighten connections if needed
Replace the faucet if repairs do not stop the leak