I can't say what works for everyone, but for me, the obvious first step is actually hearing about a book or author. If I don't find them, I can't read them. In the old days, I'd go to bookstores and browse shelves filled with books of whatever genre I was in the mood for, and I'd scan titles and covers to see what looked interesting. Then I'd read back cover copy and so on.
Nowadays, with so many books purchased online and in e-format, one can't really visually scan in the same way. If I haven't heard of an author, and if they don't get tossed up as a suggestion on Amazon, I won't find them, let alone read them. Discoverability is huge, and it's a big obstacle, especially for newer writers or writers who aren't famous enough to be widely reviewed or discussed by fans of particular genres or types of literature.
Once I've spotted a book, though, the things that lead me to want to read it are going to be influenced by the type of story, and within my favorite genres, the kinds of worlds and characters. Voice and narrative style are important too. When I read those first couple pages on Amazon, I don't buy the book if I can't connect with the protagonist, or if the voice and narrative style don't appeal to me.
Also, premise matters, along with that hook. For me, there's a fine line between not knowing what's going on in a way that makes me want to keep reading to find out vs not knowing what's going on in a way that makes me think, WTF is going on? and closing the book.
To go though my thought process of not getting into a book that was recommended to me:
First five pages some italicized drivel that doesn't say anything.
Ch 1 opens with a floridly written scene description. Pretty prose, but who is the story about? Keep reading because prose is pretty.
Another page in, story still a bunch of prettily written external description. I'm starting to get bored. Finally a character, but he's not doing anything terribly interesting--just riding on a train. The extremely external omniscient narrative is starting to wear on me. Don't even know his name. He's just "the young man." A couple pages later the guy finally has a name.
A few pages later: OMG, this character finally got off the train and is now walking home, but nothing is happening except he's brooding about his dad (whom I know from back cover copy is about to die). But things are moving so slowly.
Puts book down.
Note that this is a popular and critically acclaimed book, but for whatever reason, it didn't grab me. Actually, I have trouble connecting with quite a few SFF novels that are popular and critically acclaimed.
*Worries that she is a philistine*