Counting the Steps Between Clues
When two printed numbers are far apart, count how many steps lie between them and how many cells the path would need to get from one to the other. A gap of four numbers between cells that are four steps away leaves no room for detours.
Easy, Medium and Hard on a 6x6
With half of the grid printed, Easy puzzles mostly ask for short links. Medium grids remove a few more numbers. On Hard grids, the remaining clues are the ones the solution truly needs, and long stretches must be planned before they are written.
Mind the Corners
A corner cell touches only three others, and an edge cell five. Low and high numbers near the corners often have just one possible neighbor, which makes the corners a good place to look first.