The key is to set realistic customer expectations, and then not to just meet them, but to exceed them - preferably in unexpected and helpful ways.
Setting customer expectations at a level that is aligned with consistently deliverable levels of customer service requires that your whole staff, from product development to marketing, works in harmony with your brand image.
I am constantly pushing myself and my own expectations and have always found that I've always come out better for it. Fear is human nature, but turning fear into opportunity is what will make a difference. I would much rather look back at my life saying "I can't believe I did that," than, "What if I had done that?"