The only way to make a career decision is to let your interests guide you. Of course, you should also have an aptitude for it or things can go horribly wrong. The other thing to keep in mind is the demand for the field you want to make a career in. In case of starting a business, look to provide services or products that have a high demand and low supply.
As for ideas on starting a business, I would suggest something with low startup cost like medical transcription. Itís likely that you already have the infrastructure in place needed for setting up this business (a computer, Internet connection and a fixed phone line). The only other requirement would be to get a formal training in the field. You may want to take a look at the Career Step medical transcription training course for that!