"He's a man who always keeps his word."
"She's great -- incredibly reliable. If she says she's going to get something done, she does."
Most of it would be proud if people said these things about us. Always keeping your word is a truly valuable trait. Believe it or not, there aren't a lot of people or companies out there who do what they promise, every time, without fail.
It's also a trait that requires absolutely no skill or talent.
All you have to do is be careful with what you promise -- not giving in to the easy temptation to promise the world, when you know you can't really deliver -- and then work hard to make sure you live up to your word.
That's how you build a reputation. It's not easy, but it's simple.