In addition to straight polyethylene pipe, composite pipe, with an aluminum core sheathed in plastic, is approved in some areas for water supply and gas lines. Cut it with a tubing cutter.
Use a reaming tool to true the tubing into round and clean out the inside of the cut end. Insert the tool and give it a couple of twists. Make sure no scrapings are left inside the tube.
Slip a nut and a ferrule onto the tube end, then slip the tube onto the fitting. Finger-tighten, taking care not to cross-thread. Then tighten the nut with one full turn (no more), using an adjustable wrench or pliers.
Three simple projects to cross off of your to-do list -- just print these instructions and begin!