Name of recipient
Dear (use first name)
This should be a short pleasantry which under normal circumstances should not be related to business, such as enquiring if the recipient had a pleasant weekend.
Here, as usual for a business letter, you will use one or two paragraphs to convey the message of your letter. Be sure to be concise and to the point.
Conclusion. This should go over the points you have made in the prior paragraph(s) and thank the reader for his/her time, but you can also mention that you are looking forward to seeing them, or insert another similar nicety to give the letter a more friendly feel.