1. If the leak is at the bonnet: a. Start by tightening the bonnet with a wrench. b. If that doesn’t work, shut the water off and fully remove the shutoff and the bonnet. Check the washer underneath the bonnet. If it is worn, replace it. There are washer replacement kits that can be bought at the home center, or even packing the threaded connection tightly with Teflon tape can do the trick.
  2. If the leak is at the spout, the process is a little more involved: a. Turn the water off and remove the stem unit. b. Loosen the screw at the bottom of the stem unit with the screwdriver. It’s going to be hard to loosen, so it’s important to use the right size screwdriver and enough force to prevent it from stripping. c. Replace the washer of the stem unit and put the screw back in place. d. Take the reseating tool and push it through the opening of the stem unit. Twist it around to smooth out the seat that the stem unit rests on. e. Reinstall the stem unit and turn the water back on.

Resources:

The spare washer kit, teflon tape, and spigot repair tools can all be found at home centers and plumbing supply houses.

Shopping List:

Washer repair kit Teflon tape

Tools:

How to Fix a Leaky Hose Spigot - 32How to Fix a Leaky Hose Spigot - 46How to Fix a Leaky Hose Spigot - 50