A bit of colored silk in the breast pocket of a man's jacket is usually the step that indicates he has learned self-confidence in his dress. And the square itself is often the most beautiful item in his ensemble, though that beauty is a secret usually known only to the wearer since little of it shows.
Of the styles of pocket squares available I like the patterned silk print the best, because it is the most flexible. It is also the most difficult to find apart from Hermes, as the economics of silk printing require longer runs than most sellers find practical. But the combination of a center in one color, edges in another, and patterns adding more interest provides considerable flexibility in the look. Even adherents of the 'cram it in and walk out the door' style see a different result from the same square on different days.
In the photos, an example from Mariano Rubinacci printed with images of Neapolitan ceramics.