New Kindle User.. now what?

So I wanted to get back into reading now that I feel like I finally have the time to do so, and decided to splurge on a Kindle. And now that I have it, I guess I maybe should’ve got a better understanding on how to actually find good books. I currently have a free trial of kindle unlimited, but is there a database that shows me only kindle unlimited books? So far I’ve only been able to find a list of 29 books…?

Otherwise, I just have to buy the books that people actually want to read? Sorry if that sounds stupid for me to complain about, but maybe I could be better off with a library card?

I guess I thought it’d be like Netflix.

Do you find yourself just having to spend a bunch of money to read on your kindle? How do you determine a good book and commit to buying it? Are they priced cheaper than the physical book? And lastly, any recommendations for books that are included in kindle unlimited?