Proforma invoices basically contain much of the same information as the formal quotation, and in many cases can be used in place of one. It should give the buyer as much information about the order as possible so arrangements can be made efficiently. The invoices inform the buyer and the appropriate import government authorities details of the future shipment; changes should not be made without the buyer's consent.
Itemized List of Services _ must be specific People want to know what they've paid for. Most people will not pay for something described merely as "Design." Tell them exactly what they have received: e.g. "Design of three_page static website for Sporting Goods Department." Be as specific as possible. In five years, would both you and the client know what you meant by your description? Also, specify whether the charge is project_based or hourly.