Electrical

Leaving the stripped insulation slug on the wire tip as a grip while twisting strands — no fraying, and the copper waste comes off in one piece.

Sucking a light pull string through conduit with a vacuum, then using it to pull the wire — bends and couplings stop mattering.

A spare wall plate with drilled-out screw holes that holds multi-gang devices level while you tighten them through it.

Writing the breaker number on the back of each cover plate so the next job starts with the answer.

Checking a GFCI outlet's own Line and Load labels instead of copying the old device's wiring positions.

Raising solar path lights on pipe posts so they stand above the driveway edge instead of sitting at grade.

Shaping a cable or fish-tape tip so it glides through conduit bends and couplings without snagging.

Using a multimeter's ohms setting to catch component failures a continuity test misses.

Threading a nut onto the mounting screw as a spacer to snug up a loose or recessed outlet.

Identifying which breaker controls an outlet without trial and error.