2. Define the customer. This is very simple. YOU are the customer. Market and design the product FOR YOURSELF. Would you buy it? Do you see a benefit? Ask your friends. Most likely they are just like you. If you're going at this alone, you probably don't have time or money to do "market research".
3. Pursue what you know. If you've spent twenty years as a nurse then solve a problem related to nursing. Otherwise it may have already been tried or simply isn't necessary. Focus on a niche.
4. Carry out thought experiments. Imagine everything! The prototype. The website. The logo. The marketing strategy. This will allow for you to find faults in your idea and either abandon or improve it.
5. Test your idea. Build a prototype to convince yourself. It doesn't need to be fancy...it just needs to work. Find a way...be creative. It just may allow you to differentiate the best idea.
6. Scope out the competition. Who are the major players? What are they selling things for? What's their competitive advantage? Imagine how your product will compete. If you have the $$ attend a trade conference and ask questions, posing as a customer.
7. Gut check. Be sure that you have what it takes to see it through. Once you start spending money, you're IN! Be serious.
8. Budget. This is very difficult because you don't know what it will actually cost, until you are IN the process. But, try your best to estimate costs. Try to do things in stages that are gated. For example, invest money to create a professional prototype and THEN gauge interest before committing more money to the venture.
9. Intellectual property. Do you need a patent? Until you hire a professional to do a patent search, go to USPO and search for yourself. Two thing you need to know 1) Is it patentable? 2) Does it infringe on another patent? This is a big subject...more on it later.
10. Remove the "Idea goggles". It's easy to fall in love with our ideas. It's human nature to focus ONLY on the positive. BUT, try to kill your idea at ever step. Always play devil's advocate. Don't throw good money after bad just because it's your baby!