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. Include Your Terms _ must be clear When do you expect the client to pay you? What happens if they miss the deadline? To be able to send follow_up or overdue notices or to charge interest, you need a rock_solid paper trail that no one can argue with.
How you present your bills for payment to your clients may not seem as important as, for instance, the quality of your services or the products offered _ but actually it is. Are you still using the traditional invoicing? Your clients won't be too enthusiastic when forced to put aside a good portion of their valuable time in order to sort through your paper invoices, file them and maintain payment timelines. You, on the other hand, will have to put up with the hassle of managing all that paper: can you really afford to lose so much of your time on paperwork, when it's better spent working on other aspects of your business?
Thank Them, and Ask Them to Thank You _ must be sincere Money is often a touchy subject, so politeness about it is a good idea. Your clients are paying you money that they've earned with blood, sweat and tears, so let them know you appreciate it. You should also invite them to contact you if they have any questions and, more importantly, make it clear that you appreciate their present (and future) business. Some people also welcome testimonials; for example, by adding, "Let us know how we did. Write a testimonial and sent to... " If you're building your website's testimonials page or want to complete the feedback loop, this is a great way to get clients to give feedback on your work. If they have suggestions for making the process smoother, it's also a great opportunity for you to improve.