Communication is your friend. When you are selling your services to a potential client, always keep in mind that what you know isn't always what they know. You may forget to include all the great details that would really sell your company and land you the contract.
For example, you might make a statement like this, "We provide outstanding service to all our customers." It's a great thing to say to people but if you stop there, you're not communicating. Why is your service outstanding? What do you do to make it so great? Do you do something different from your competitor? Talk with the potential client, don't talk at them. You know that you offer 24-hour emergency service or that the products you install have a 10 year warranty. But these people don't.
"We have X years of experience in this industry." Doing what? This is a great jumping-off point but it has to be taken further. Break down those years and share the type of work you've done and demonstrate your passion for you've been in this business for so long.
"I'm confident we'll do this job right." I'm happy for you. But communicate with me why you're so confident. Do you have new state of the art tools? Do you use only the best materials? Does everyone on your team have 10 years on the job? Make them confident.
"We do this job better than anyone else." Very good. But... you know what's coming next. Give us the details, right? Right. Let them know why you're the expert. Tell them what they need to know and maybe what they don't need to know. If they see (and hear) you are capable, they will sign on the dotted line.