I got my staff to try out WHMCS, and while it is user-friendly, a knock against it is, they make you pay to remove their logo or "powered by" line. I'm not sure how it is now, but if I pay for a license, I want it to be branded.

Also, you don't need a billing manager to get setup. While it does look professional, I started in 2001-2002 without one, and it didn't hurt sales. Personal customer service, value added services, a niche market, unique offers...all of those will help you attract a good client base.

Also, don't make an overly complicated website. Keep it clean, simple and easy to use, with one click access to most information, and you'll be good to go.

Best of luck.