Will your new business be a success?
A startup is a business that provides a new idea, process or product. If this is your business model then it makes sense to test out whether its just you who thinks its a good idea or whether its a paying proposition.
You can do this by spending a couple of hundred dollars on Google Adwords before you spend thousands developing a website or apps etc. Use a tool like the Google Adwords keyword planner to search for words that potential customers are looking for.
This article by Inc. asks 8 questions which will test your new business concept and is worth a read.
Other products like QuickMVP may be able to assist you with this process. You can try that product risk free. They make it easy to build landing pages to test your product.
If your looking to start or buy a conventional brick & mortar business then you will want to speak with your accountant to make sure your business plan is feasible.