The best way to close a deal is to be genuine and transparent. There is no magic word or phrase that makes it happen. You need to know who your ideal client is and know your product or service. Listen to the potential customer and determine what they are looking for and how you might work together.  Once you discover if the relationship would work well with them, you will find that bringing them onboard and "closing" the deal will be easier. You can already picture how you will work together. Describe what that would be like and how you would help them with the services they are needing.