How can one find journals paying authors or reviewers? How can one find journals paying authors or reviewers? 
I've read about some old examples (probably about a relatively small university I can't recall) but I'm wondering if is there a directory or shared keyword or do they just go by word of mouth?
Can I write on topics I don't have a PhD about but I'm otherwise competent on?

Thank you
Write for almost anything else than scientific journals and you can get paid. 
Also, if you are not doing research / don't have a PhD in a topic, something else than scientific publishing is much more easier.