There are many many many style guide books out there, especially that have come out in the past few years. I like these two because, while the tip every style guide ever gives you is "be yourself", these books actually show you how to do just that. No matter how "yourself" you're being, just about everyone needs to have a look they're channeling, an idea, a mood, an ideal version of how they see themselves. The Lucky Guide helps you find that by showing 10 classic "looks" -- gamine, boho, bombshell, and everything in between -- how to achieve them, and then how to mix and match so you don't look cliche. The Mizrahi guide has an elaborate system of finding your own style that he goes through, from creating a look board to going through your own closet critically to creating polished dream looks. And each of the women he helps in the book ends up with their own distinct style that you can tell really matches them.
I'm not so crazy about all the "A to Z" guides, because they basically just list fashion elements and describe them, rather than helping you pick and choose for yourself. Not everyone can walk around in a classic white shirt, trench coat, scarf, stilettos, and so on, and not look boring or just plain bad. So in my opinion if you already know what dolman and peplum and poplin all mean and are looking for a little more guidance, these guides aren't for you.
Are they any style guides you like or use? It's always great to find a new one that really works.