Diversify if you can. If you can write nonfiction essays and articles, too, do it. If you can write nonfiction books, great. If you're good at teaching, add that to your arsenal. It's not that you can't still make a full-time living at fiction, but that the marketplace is more volatile and thus you need to be able to emphasize some other part of your skillset if there's a year where things get rough. Also, most definitely still pursue traditional publishing/publishers, but do have a little bit of a self-publishing space out there, too.