Start by finding out what people need. Go to Facebook groups, LinkedIn groups, Quora questions, Reddit forums and start reading about things that interest YOU. That will ensure you're in a space you can stay interested in. However, look at problems other people are having. Think of ways you can solve those problems. Those solutions will help you come up with ideas for businesses. Approach it from the standpoint that you are going to learn and understand before you try to sell. Once you know enough about the problems your potential customers may have, creating something for them to buy will seem much easier.