Click to see the full essay. This is my summary, quoting and paraphrasing the content.
Look for problems, preferably problems you have yourself.
Something you want, you can build, and that few others realize is worth doing.
Ensure the problem really exists.
When a startup launches, there have to be at least some users who really need what the startup is making, who want it urgently.
Build something a small number of people want a large amount. Nearly all good startup ideas are of that type.
Live in the future, then build what’s missing.
Err on the side of doing things where you’ll face competitors.
The place to start looking for ideas is things you need.
The next best thing to an unmet need of your own is an unmet need of someone else.
Ask what you wish someone else would build, so that you could use it. What would you pay for right now?
The users' need has to give them sufficient activation energy to start using whatever you make.
Trying to sell something bad can be a source of better ideas.