From A List Apart comes these tips for creating better invoices. The article contains advice on invoice contents, terms, delivery, timing, and aesthetics. Some really good advice for any business person who sends out invoices on a regular basis (Lawyers, are you listening?). My favorite part is the section on invoice content:

1. The word “invoice.” Obvious enough, but don’t let the client mistake it for anything other than a bill that needs to be paid. Make it big and bold and put it at the top of the page.
2. Your Employer Identification Number (EIN) or Tax ID Number. This will be important come tax time, when the client starts putting together W-2s.
3. Similar to the EIN, some clients may assign outside contractors a unique Vendor ID. This practice is usually found in larger companies. If you have been given one, be sure it appears conspicuously.
4. Names and addresses of both client and contractor. Make a clear distinction between the “to” party and the “from” party.
5. Date everything. Date the invoice (the day it goes out, not the day you write it) and list the dates of when items on the invoice were completed. In the terms, list the due date and penalty dates. If something ever goes to small claims court, the judge will look favorably on your scrupulous attention to detail.
6. A clear, itemized list of services rendered. Descriptions should be short and to the point, and all delivery dates indicated. Next to each item, list the hourly rate, hours worked and subtotal amount.
7. The total amount owed. On the bottom, labeled explicitly, bolded if needed.
8. The terms of the invoice. At the very least, this should include when the invoice is due; for instance, if you expect payment within thirty days (fairly standard), simply put “30 Days.” (You could also put “15 Days” or even “Immediate” if you don’t particularly like the client.)

As I read the tips, I remembered the hours and hours I've spent on my office's legal accounting programs trying to get good-looking, informative invoices to print with the information I needed. PCLaw's prepackaged invoices were absolutly awful (I've not tried versions 6 or 7), and the template "editor" was an exercise in futility. We've moved to Quickbooks and are rolling out a new invoice design, which incorporates most of the tips from the article. I'll try to post a sample soon.