Make every word count. It's not just good advice. It's what your editor expects from you. Everybody knows adverbs are the devil, right? Your characters don't need to dance gracefully or smile happily (though we might need to hear about it if they're smiling sadly.) But it isn't just extra adverbs that gum up the works of your manuscript. Here are a few other superfluous devils to consider:
1. Wordy structure: 'The pages of the book were yellow with age.' Why not 'the book's pages'?
2. Echoes or overused words: We've all got 'em. Mine are 'tiny' and 'just.' Oh yes, everything I write about is just tiny. And then there are manuscript-specific ones. For Venom, they were 'murky' and 'cavernous.' Murky canals and cavernous palazzos on every freaking street corner. Usually you can pick these out in revision, do a 'find', and replace as necessary. Alternatively, you can paste your whole manuscript into a wordle and it'll give you a cute graphical representation of your verbal crutches.
3. Redundant or excessive modifiers:' The frigid, cold winter.' Simplistic, but I see this construction all the time. 'A thin coating of snow, luminous and iceblown, encased the car is a shell of crystal white.' Sounds good, but what is it really saying? Anywhere you are using two adjectives to modify a noun, I would ask yourself a) if you could show instead of tell and b) do you really need both?
4. Extra prepositional phrases: 'Cass sat up in bed.' If your character has been dreaming or sleeping, chances are we know they are in bed. 'Sam glanced around the room and was surprised to see a rabid chicken advancing.' Why not just 'Sam saw a rabid chicken advancing'? (and then show the surprise.) 'It's in the third drawer of the wooden dresser by the window in your bedroom.' Do you really need all that? Maybe you do. The idea is not to strike all the prepositional phrases, just to recognize them and make a conscious decision as to whether they add anything.
5. TM freaking I: It's the Moby Dick phenomenon. Maybe you're an expert in marine biology. Cool, but kids reading your fun MG adventure about a boy who falls off a cruise ship and gets saved by a pod of dolphins don't care. They don't need to read two pages about what dolphins eat. They just want enough description/information to visualize the pod, to feel like they're really there. Plus, if you fell off a cruise ship would you really be watching dolphins eat? No, you'd be freaking out, wondering if you're going to die, and watching for sharks. Well, I would be anyway.
6. Body parts doing their own thing: 'My eyes lifted upward, ever so slightly.' 'My feet carried me away from the brawl that had just broken out.' 'My fingers reached out to touch the stubble of his beard.' There are some places where this kind of writing might be best for tone or style purposes, but again, you should be conscious of your characters' wayward body parts. Unless her eyes are lifting upward while the rest of her is collapsing into a puddle of blood in the street, 'I glanced upward,' probably gets the job done. Did I mention 'glance' is another one of my overused words?
It's not just about weighing down your manuscript with clunky writing; it's also a financial matter. Longer books cost more to edit, copy edit, and produce. As someone whose debut novel weighs in at a hefty 113,000 words, I can tell you that my editor and I were grateful for every single syllable we were able to trim away without sacrificing the story.