Tackling LJ Shen's interconnected universe can be a bit of a puzzle at first, since her characters tend to pop up in each other's stories in a wonderfully messy way. The good news is there are a couple of clear paths you can take, and which one you choose depends on how you like to experience a series. My suggestion for a truly cohesive experience is to follow the internal chronological order of the stories, rather than just publication order. This means starting with 'The Kiss Thief,' which sets the stage for the entire 'Sinners of Saint' and 'All Saints High' world. From there, you'd move into the 'Sinners of Saint' series proper, beginning with 'Vicious'—that's the one that introduces the infamous Vicious and the whole complex dynamic of that friend group. Following those core books naturally leads you into the 'All Saints High' series, which focuses on the next generation. This route lets you see cause and effect play out in a really satisfying way, as the consequences of the parents' actions ripple directly into their kids' lives.
If you prefer a more streamlined dive into her most popular characters, you could focus on the 'Sinners of Saint' series as a complete block: 'Vicious,' 'Ruckus,' 'Scandalous,' 'Bane,' and 'Pretty Reckless.' This cluster gives you the heart of her early work and those famously flawed, magnetic anti-heroes. The standalone 'The Kiss Thief' technically comes before these, but its ties are more thematic than direct, so jumping straight to 'Vicious' won't leave you lost. For the 'All Saints High' spin-off, which follows the children of the Sinners, you'd want 'Pretty Lies,' 'Pretty Mess,' and 'Pretty Venom'—reading these after the 'Sinners' books makes all the rivalries and inherited tensions hit much harder.
Ultimately, the connections are more about cameos and shared world-building than a strict, linear plot you must follow in sequence. I found that reading by series—finishing one set of linked characters before moving to the next—kept me from getting whiplash jumping between timelines. The most important link is probably between the original Sinners and their kids in All Saints High, so keeping those two groups in relative order is the key to catching all the nuanced references. The emotional payoff when a character from an older book makes an unexpected appearance is one of the real joys of her work, and a sensible reading order just amplifies that.