Literature

When I see a book mentioned enough times in contexts generally aligning with my tastes (also depends on how much I trust the context: an ad will have near-zero impact, a direct recommendation from a close friend will have high impact, for a review it depends), I decide to give it a try.

As for your situation, you'd benefit from having a reviewer with good taste and solid reputation. It might be quite a challenge, but it's probably worth it once you've made sure your book doesn't suffer from trivial flaws. Or, if it's just a hobby, you might choose not to bother, or to have more practice first.

I pretty much exclusively do the WRONG thing and judge a book by its cover.

Mostly word of mouth and reading online reviews. r/suggestmeabook and r/weirdlit were great resources for me as well.

Since I primarily read via the library, I'm not really worried about "wasting money" on books I wind up not liking, so I can be more adventurous with reading new authors I'm not sure about.

Word of mouth, NPR interviews/segments, or if I flip through it and I vibe with what little I can skim. Also if it's non fiction and especially historical non fiction about something I'm interested in I'll def read it.

A good portion of my library is hand me downs from my in-laws. Luckily they are really cool people and have good taste.

Usually word of mouth - but that can be either from people I know (friends, fellow online people), or sometimes it might be buzz from the media. Usually that's in the form of CBC's Canada Reads. I don't often pick things up based on retailer suggestions.