What are your assumptions of your solution that makes it risky for your business? List them each on their own line.
Businesses fail because their assumptions are wrong, and they didn't make necessary precautions to address those false assumptions. When you guess that a problem is a problem, that is an assumption. When you assume that your solution will solve the customers' problem, that's an assumption too. The features you later define for your product will be assumptions too.
What are the assumptions that are not proven, and can seriously affect the operation of your product in the future?
Assumptions are best resolved by asking users or interviewing them.
In the future when you have the product ready, you can also monitor your users' behavior so that you can collect data and understand whether or not your assumptions are correct.
Example: StartitUp's riskiest assumptions are:
1. Assuming entrepreneurs like to learn or build their startups in step-by-step style.
2. We assume that our guide can really help startups build, grow, and get funded.
3. We assume that entrepreneurs will like to help each other.