A lot of people want to start a startup — but they don’t know where to start. And where there’s plenty you can do to get the ball rolling, there’s actually one place that everyone has to start: The idea.

But, what are the best startup ideas? What are the worst?

Before we dive into that big question — one disclaimer:

This is not a plug-and-play list of startup business ideas that you can cherry pick from in order to create the next unicorn startup. (That doesn’t exist. If it did, everyone would actually be killing it, all the time.)

Instead, we’re going to talk about some general categories of startups that are more or less difficult to start, help you figure out how to pick your best startup idea, and talk to some founders about their expe...