Never start in a corner
Corners are rarely square; layouts that start there inherit every error and distribute it outward. The professional move: snap center lines, dry-lay a full row both directions, and shift the grid so cut tiles land symmetrically — or so the cut edge hides under the toilet and toe-kicks. The best-looking line in tiling is a planned one.
The three rules
One: no sliver cuts — a cut under half a tile width reads as an error; shift the layout to make cuts meaningful. Two: cuts land where eyes do not — under vanities, at doorways. Three: check the sightline from the door — the row you see first is the row that must be straight and uncut.
What the dry-fit catches
Wrong waste factor (visible cut count), dead tiles (unlevel floor discovered early), and layout surprises (a 2-inch sliver at the shower curb) — all fixable on dry-run, all expensive once mortar is open. Twenty minutes of tile without glue is the cheapest quality control in renovation.