The common advice, if you want to start a business or venture, is to start with what you’re passionate about and find a market that is also passionate about it.
It’s not a bad strategy, but I think an even better strategy is not to force the issue. Instead, start with the terrain.
Don’t find something you can do well at. Find something – a field, a niche, a market, a topic – you can study. Something you can spend hours learning about. Don’t think about business ideas, just study the terrain. Study its cool parts and study its problems.
Participate in discussions, give some pointers, teach people who know less than you. Allow yourself to fall in love with the terrain, to care for it.
Over time, because you care, you’ll start to see little gaps to be filled, gaps only you can fill. You’ll start to see how to win on the terrain. It takes time, but with that time, you’ll be gaining a much better picture of how you can actually contribute.
Whatever enterprise you come up with, it won’t be based on “what you’re good at.” Rather, it’ll be based on problems you really care about. And because you care, it’ll be much more likely to help.