I was in the same boat as you. Recently I expanded by business from solely PC Maintenance, sales and repairs (I am qualified PC Technician) into Web Development and Print Design. Where print design has specific requirements, I outsource this work (for a finders fee) to a friend who has over 10 years experience.
The beauty of a service is that it is a product you manufacture, and therefore, you can determine the cost per unit and the amount you think you are worth to your customers. I have only 2 months experience working for a professional design studio, from there I have only been playing around with Ps, Dw and Flash. When I moved my business into web design, I did have some customers all ready to rock and roll, which certainly made it easier, and I charged only $395 for what was well over 60 hours work on each site. However, it has given me the opportunity to have sites online that link back to me, as well as some sites for my portfolio. After 2 weeks of completing those 2 sites, I scored another 2 customers which were referrals from my first 2 customer websites (they clicked the link at bottom of page). Last week I earned $1800 including web hosting, print and web design, and am near completion for both sites after spending only 10 hours on each.
I think the key is networking, and analysing other designs. I have subscribed to several forums, magazines and constantly review other websites, to keep up-to-date with current trends, styles and methods of delivering content effectively online.
Keep it up, and dont give up. It can be hard at 3am trying to work out why IE is showing no gaps between paragraphs when Firefox and Opera show it perfect, lol, but it gets easier. As you grow in confidence, and you feel you are worth more, invest more into your site and the quality of your service, and increase your prices.
Good luck!