Backwards solving

Some people like to solve a puzzle by tackling the clues strictly in numerical order. Some people like to toughen up an easy puzzle by tossing the Across clues and using only the Down clues. Sometimes I work through a puzzle (in Games or Games World of Puzzles, not my regular diet of Across Lite crosswords) by branching off the first word, then off the second word, filling in a path through the grid.

Recently I started using a new method—beginning with the last Across answer, I fill in the grid backwards, from the lower right to the upper left corner. Occasionally some of the letters wind up backwards when I'm writing from right to left, but hey, nobody else has to read it.

Try it out the next time you've got a Mondayish puzzle and nearby eyewitnesses.

Next, I'll try upside-down solving.

What's your favorite self-imposed solving constraint, and how often do you use it?