1. Use grip surface material with low thermal conductivity, such as rubber, wood or plastic. Metal has high thermal and electrical conductivity and can be dangerous.
2. For metal handles, even a thin layer of plastic (e.g. a sleeve) can greatly reduce thermal conductivity and increase grip comfort.
3. In the case of electrically powered hand tools, use grounded plugs and double-insulated tools (where the handle is insulated from the power).