1. Your hook is NEVER a landscape description
Your hook, which is 99.9% of the time your opening line, is ALWAYS about the people.
Declarations are far more interesting and engaging than a landscape description. For example, don't these three opening lines draw you in instead of making you yawn:
"It is the first of November and so, today, someone will die." --Prologue, The Scorpio Races, Maggie Stiefvater
"People say my brothers would be lost without me, but really, I'd be lost without them." --Chapter 1, The Scorpio Races, Maggie Stiefvater
"Blue Sargent had forgotten how many times she'd been told that she would kill her true love." --Prologue, The Raven Boys, Maggie Stiefvater
"It was freezing in the churchyard, even before the dead arrived." Chapter 1, The Raven Boys, Maggie Stiefvater
2. Multiple Points of View are for exploring major characters from different perspectives
I used to hate multiple points of view with a passion. I would usually drop a book back into the pile if it switched between two or more people. But then I read The Raven Boys and when I reached Adam's POV where he dug further into Gansey's personality and character and gave us a deeper understanding of him, I finally found a powerful use for multiple POVs and a reason to love them.
Take a look at this quote from The Raven Boys.
"This is why Adam could forgive that shallow, glossy version of Gansey he'd first met. Because of his money and his good family name, because of his handsome smile and his easy laugh, because he liked people and (despite his fears of the contrary) they liked him back, Gansey could've had any and all of the friends that he wanted. Instead he had chosen the three of them, three guys who should've, for three different reasons, been friendless." --The Raven Boys, Maggie Stiefvater
Boom. Suddenly, you know more about Gansey and Adam both than you did before, and boom, you love them just a little bit more.
Multiple POV has many uses, but I think this kind should be utilized much more often.
3. There is always a bigger story underneath
Just on the surface, I fell in love with Blue, Gansey, Ronan, Adam, and Noah, and their search for a dead Welsh king. Puck and Sean, from The Scorpio Races, will always be my favorite characters. But Maggie Stiefvater took everything you loved and blew it up to something way more complicated and intertwined than I ever thought possible, taking roads and dimensions so completely unexpected and making them work, especially the dreamworld dimension. Never expected any of that. She's pretty much a master at this.
Always, always look for the bigger story underneath. Always say to yourself, "Ok. So I know this is happening. But what's REALLY going on here?"
4. Never write down to a teenager, especially in YA books
Maggie is not afraid to write anything that today's teenagers might "not get." And this goes all the way from characters who are much more grown up than their years, to plot and grammatical form. She doesn't write simply just for the age genre.
She writes characters, namely in The Scorpio Races and The Raven Boys, who think like adults, who know more than their age requires because they are smart and intuitive, and it is a part of who they are.
I believe this is one of the most important things you can do as a YA writer today. Never not write something because you don't think your audience won't understand it. Because youth today need something to sympathize with AND aspire to. They need to be looking forward to being a better person, not assurance that they can stay in their comfort zone all their lives.
5. Never be afraid to break rules
This wasn't so much something I learned as it is something I always seek affirmation for. And Maggie affirmed it for me a million times over.
Maggie breaks all the rules. From structure, to character arc, to grammatical formatting, to chapters that are only a few paragraphs long. And she does it published.
Always strive to be original.
Always be creative.
Rules are rules. Except when you're a creative.
Then you get to get really creative and discover all the ways you can break the rules.
Maggie Stiefvater is a master of breaking rules.