The path I took was to write libraries for a large ecosystem (Laravel) to solve gnarly problems I was having. The gnarlier the better. Pick the thing that nobody else wants to do and solve it. That's what I did, no guarantees that'll work for anyone else though!

most of the exposure you’ll be getting is from organic search

you might not realize, but people are literally searching for solutions all the time

companies also search for projects they want to build/use to see who’s already building it (this is where you can get hired)

so, a good idea would be to work on your README so when your prospects describe the problem to the search engine your project comes up as a solution

then make sure the technical side and the documentation are solid, so that people can depend on it

a plus for you would be to have projects across multiple domains, this increases your exposure

if you want to go a step beyond that, try to post your projects to relevant communities (note: this should come secondary after search)

My emphasis was probably a little off. You might be answering something like "if my goal is a strong profile, where should I start?" I was a little more curious about "where do you think ~strong begins?"

In any case, "people depend on it" and "projects across multiple domains" both seem like good-enough answers to the latter question.

Better yet is fixing those bugs and opening pull requests.

Or just mining the bugtracker to fix bugs other users encountered.

Its a solid place to start - getting known as a useful contributor to a handful of projects can work wonders.