You are the only one that can figure that out as every situation is unique. You need to find an unmet need that is also something you like to do. Complete a SWOT (Strengths, Weaknesses, Opportunities, and Threats) analysis and write a business plan to prove that the business idea is workable. Go to http://sba.gov/smallbusinessplanner/plan/writeabusinessplan/index.html or http://www.score.org/template_gallery.html for instructions on how to write a business plan and sample business plans.