0 Beside a 3

Medium Used by Smart Hint

A 0 next to a 3 settles the 3 outright: the shared edge is blank, so the 3's other three sides are all lines.

Edge the technique adds
Edge ruled out
Cells that establish the pattern

How it works

The 0 rules out all four of its own edges — including the one it shares with the 3.
That leaves the 3 with only three sides it could possibly use, and it needs exactly three.
Draw all three: the 3's top, bottom, and far side. The whole cell is settled in one move.
This is the single most productive opening pattern in the game — scan for every 0 first, then look at what it touches.