Picking the right cutting, gripping and checking tool for the job, and using it safely.
Cutting pipe
A rotary pipe cutter (pipe slice) gives copper tube a clean, square cut with very little swarf, which helps the pipe seat correctly in a fitting; it can still leave an internal burr, so deburr the cut end whichever tool made it. Rigid plastic waste pipe cuts best with a fine-toothed saw and a mitre block, or a purpose-made pipe cutter, then deburred and chamfered so it seats in a push-fit or solvent-weld socket.
Gripping and turning
Tighten or release a compression fitting's nut with an adjustable spanner, or a correctly sized open-ended spanner, sized to the nut's flats. Toothed grips such as water-pump pliers or a pipe wrench can round off the flats and damage the nut. Behind a sink or basin, where there is no room to swing a spanner, a crowsfoot basin wrench reaches the tap's back-nut with its long shaft and swivelling head.
A press fitting must be made with the tool and jaw profile the manufacturer specifies, kept serviceable and in calibration. The correct jaw forms the joint to the intended geometry and force; a worn or wrong jaw can still complete a press cycle while leaving a joint that leaks or fails later.
Checking before you start
Give a power tool's lead and plug a quick visual check before use, looking for cut cable, a cracked or burnt plug, or a loose connection; this complements formal PAT testing rather than replacing it. Before drilling into a wall to fix a pipe clip or bracket, use a cable and pipe detector to check for concealed services, since drilling blind risks a live cable or a buried pipe. A spirit level checks that pipework or an appliance is truly level, or set to the fall a drain or waste pipe needs.
The right tool for the job
Using the correct tool, rather than improvising with whatever is to hand, gives a safer and more reliable result. The wrong tool stays hazardous even used carefully, and a tidy work area, with offcuts, leads and tools cleared away, keeps access and escape routes free of trip hazards.