Restraint is a key factor in all the art that really moves me.
Example: music. If a guitar player goes nuts for an entire song and pays no attention to dynamics, I don’t care how technically good he is or how much he shreds, my emotions are dead.
It’s not just art. When a person tries too hard to make a good first impression and smothers an organic conversation with self-assertion, I start looking for an exit.
Under-do it. Leave people wanting more. When you leave it all on the table, you take away the suspense and people lose all reason to pay attention.