It's great to say what you'll do, but it's even better to back that up with evidence of what you've done, whether it's your track record, your agency's track record, or glowing testimonials from past clients.
Also, remember to make a habit of asking for recommendations as you close each transaction--LinkedIn is an easy way to do this.
(If you'd like to read our LinkedIn recommendations, or write us one, check out them out here:
http://linkd.in/XrIBSB)