Use a five gallon bucket as a tool holder. And if a leak springs mid-project, it'll catch the water. A tool caddy can also be attached to the bucket providing a place for everything. Keep a forced cup and a regular plunger handy. Each plunger has its own specific use and provides extra unclogging power. Wrenches are essential in plumbing. A pair of medium sized slip joint pliers and an adjustable wrench should cover most jobs, along with various sized wrenches. A multi-bit screwdriver can reduce the number of tools that need to be carried around on the job. An assortment of Allen keys is very handy and has many uses.