Do what you say you’re going to do.
If you (almost) always do what you say you’re going to do, people will love you for it.
We are all very good at identifying who is reliable and who has a habit of not showing up or not delivering.
It’s a great differentiator to use at work, too. Rather than being the person who works the most hours, or who responds to emails the quickest, be the person who always does what she says she’ll do.