How do you chose what fiction book to read?

Yes, I will also always read a few random sentences on a page from the middle of an unfamiliar book if I'm deciding whether or not to buy it.

Do you mean in a book shop, or how do you know what you want to read next from books you already own, and may have already read?

I think we shop for books very differently, OP. I will absolutely browse in charity shops, or Oxfam Books and the like, but generally I'll be on the lookout, whether in a new bookshop or a secondhand one, for the work of authors I like, or topics that interest me if non-fiction. I went into a local bookshop last week to pick up a book I'd ordered (the artist Dora Carrington's letters), and came away with the new Lily King, Heart the Lover (because I'd loved a previous novel of hers) and a deeply odd, critically-acclaimed novel by someone I used to know.

The house is full of books, and there's just an urge that arises to reread an old favourite, and I will then tear the place apart looking for it. Someone mentioned Barbara Kingsolver the other day, and as a consequence, I've reread three of her novels in a row.

There are genres I know I’m not interested in, so I don’t even consider those. Within genres I like, if it’s by an author I love I buy/borrow (I use the library a lot) it. Otherwise, I read page 75, and if I like it, I get the book. Works more often than not.

I read really quickly. I seek out book series so I have a run of books to read before I have to choose again.

I’m much more likely to pick up nonfiction on spec. Fiction will either be recommended on the 50 Bookers threads, a book club choice, or read about in an article (booker prize etc). I run a Wanted Books list on my phone so will sometimes order one of those, or pick it up if I see it. But even that list is heavily weighted towards nonfiction.

I have been much less likely to use the library recently due to job issues - that was where I picked up fiction on a whim.

I read the description and a page or so to see if the book feels like something I might want to read. If it gets my attention easily and I like the writing style, I usually go for it. And, yes, if I know the author and like his/her books, then that too is a factor.

I often choose books from charity shops too and totally agree with what you said about giving up on it if you can't get into it . . . these ones get donated back to the charity shop

There are a few authors I really like so I usually buy new copies of those

I'm fortunate that my sister and a couple of friends have similar tastes so we often swap books and they often buy me books for birthdays/Christmas

It depends. Sometimes I'm in the mood to browse and will pick one that looks interesting based on an assessment of the author, subject matter, cover etc.

Other times I'll have a specific book in mind because I've seen it reviewed or someone has recommended it to me.

And sometimes something catches my eye and it's spontaneous.

Really I shouldn't be buying books at all bases on the size of my 'To Read' pile, but I always say reading and book buying are two distinct hobbies!

Sometimes I read a novel a day so whatever's to hand. If I had a charity shop like yours I'd definitely follow your approach to have several appealing ones at home at all times.

I have a general idea of the kind of fiction I'm likely to enjoy, so if looking for a novel, I tend to browse and read parts to see if it catches me.

I just pick one that appeals, researching books sounds too much like school work.