Tip for authors with a novel to submit to publishers:
Pay attention to what's on the first page of their website.
Are you immediately welcomed as a writer?
That's not always a good sign.
It might be that the press is new and still building its list of authors, so it has more to say about submissions than about the books it's published. That's not awful, but not awesome either (you may prefer to wait and let them make their beginner's mistakes on someone else's book. If the publisher finds its footing, you can always submit to them in a year or two!). Or maybe they just recently opened a new call to submissions and have that prominently announced. That's fine, but also look at when and where they post about new book releases.
A publisher should have a website that appeals to readers - with descriptions of the kinds of books they do or will publish, and ways for readers to connect like a newsletter signup option and social media links. If they have already published books: how easily can readers buy them? What do the covers look like? Do the book descriptions have any obvious typos? Do multiple books or pages on the website have errors?
No matter how proud a publisher is of how they serve authors, the main job of a publisher is to get books into reader's hands. That shouldn't be an afterthought on the website. If it takes you a few clicks to find submission guidelines, that may be a good sign. If, along the way, you spot several books to add to your to-read list, that's a great sign.
If the website seems to be downright screaming "Please let us publish you!" watch out for a catch. They might not be a vanity press, but they could be. Search "[Publisher name] scam" or "[Publisher name] legitimate" or "[Publisher name] vanity" and see what comes up. Or the business might be completely legit, just with a poorly organized website. Suggesting they're not great at selling books. Still not a good sign.
Always check the Amazon listing (and other listings) of the books from a publisher you're considering. What do the reviews say? What are the sales ranks like? What formats are the books offered in, and at what price point? Do you like the covers? Do you like how the sample is formatted, and can you spot any errors in the editing or formatting?
It's better to be unpublished than badly published. Don't get your rights tied up in a contract with a shady or ineffective publisher.
