I didn’t quite understand that either. Do they mean a thread in a post that was on r/all?

Use the obvious stuff. If the goal of sharing is people seeing your photos, the more obvious the better I figure…

As for selling, think of what anyone you know might actually buy. The only photos anyone I know has actually bought are photos of their children or themselves during their wedding.

Even with famous or professional photographers, normal people don’t buy their photos directly, companies do. We buy stuff that happens to have their photo on it or were advertised with those photos. Try taking photos for a local diner’s menu or call local website developers and see if they need a photograher to take photos of their client’s business for a website?