Credibility is the most important thing to have to grow any business.
Having credibility makes you trustworthy and trust gains loyalty.
So how do you build yours?
The easiest way is to keep your promises.
Do whatever it is you said you'll do.
Deliver what you promised. Arrive on the time you said you'll be there.
Don't be that person who casually throws out promises only to break them and utter a new set of promises soon after.