Your eBay "About Me" page is a very important, and often under used, piece of virtual real estate. It is a place that provides a vehicle for you to let the first time visitor to your eBay listings or store learn more about you, your product(s) and/or service(s).
I've seen it said often that your "About Me" page should not be about YOU, but I disagree. The Internet provides a generally level playing field for small and large businesses alike so what separates you from the big guys and the other guys? It is YOU. The unique qualities that YOU bring to YOUR business. Use your eBay "About Me" page to share with, and inform, others about these qualities. Tell them -- show them -- why dealing with YOU can be different. Use your eBay "About Me" page to separate yourself from your competition. Explain what makes you, and dealing with you, the better choice.
Don't try to sound "professional". Write in a personal, face-to-face, style just as if you were there with the reader telling them, explaining to them, what you have to say, what you have to offer. Provide the necessary information without getting too technical. That's what websites and follow-up pages are for. Be confersational but concise. Be professional without being formal. Don't use jargon. Explain things in easy-to-understand terms anyone can understand. If you have trouble writing what you want to say find someone to help you. This is a key element of your business and it should be done right.
Include a picture of yourself and, where suitable, pictures of your workspace. Provide a brief bio. Show people you are serious about what you do and how your experience supports your efforts. Have good quality pictures that reflect the good quality of your business. Let people know you are a real person. That you provide real service. That you will get back to them personally -- not through some automated response system.
Update your eBay "About Me" page periodically so there is new, fresh, information for returning visitors. Provide new information, news about new products or services, and new pictures. If there isn't anything new to say, re-write existing information to say it differently.