Helping a small service business to come online is an excellent way to build a business for yourself. There are hundreds of thousands of small businesses that have very little online presence, and you can use the skills you have for online marketing to set them up as well. This will bring them more business while you develop your own system for doing this for others. This can be the start of a whole new business for you.
My recommendation is to do this for a friend or family member first, just to learn how to market in this way. I started by doing some publicity and marketing for my Rotary Club, and then I did it for a family member who works as a handyman. I Googled the handyman and saw that he was not listed on any of the first ten pages for his city and the term handyman. Then I began to blog for him, wrote several articles, and sent a free press release. Within just a few weeks he was on page one of Google for people searching in his city.
Once you have achieved some success, you can offer your services to others for a fee. Find out what they are spending for print advertising, and charge around the same amount. That way they can use your services for a month to see how well online marketing works for them. Typically small service businesses have no idea how many more people will be able to find them once they have an online presence besides a static web site.