Books in the Dirty series and the spinoff Players series are interconnected standalones, meaning you can pick and choose which ones you read, in any order, but you will definitely get the most out of the series, the individual books and the relationships within if you read the books consecutively. There are ongoing storylines that develop throughout the series, so reading them in order is not crucial but is highly recommended. I always recommend starting with Dirty Like Me (Dirty #1).
The DEEP series is a standalone duet, meant to be read in order; the story begins in book 1 and ends in book 2.
