Making a grid deduction puzzle

When making a grid-deduction puzzle, what are the strategies in making it?

For most grid-deduction puzzles, simply putting numbers/dots/whatever in the grid simply doesn't cut it. However, sometimes you need to fit a certain constraint, such as the answer looking like a certain letter.

How do you go about it?

Please post different strategies as different answers, with the strategy name at the top and an explanation beneath. Try to include an example if you can. No need to spoilerise!

I am interested in both general strategies and those for specific puzzles, so post both!