A while ago I blogged about being drunk on words, and why it's a good sign in a beginner. Too many would-be writers think their writing is spare and muscular, when in fact it's just bald and impoverished. But if the writerly teetotallers are guilty of underwriting, then the inebriates are also guilty: of over-writing. "It's overwritten" is a very baffling reaction to your work, even though it's a common one. The problem is that overwriting is very easy to feel, but even as a teacher I find it quite hard to analyse. So when a friend asked me to decode a comment about their writing being overwritten, I had a think. And these are some of the reasons, I'd suggest, that your writing might seem overwritten to others:
1) Too many adjectives and adverbs tacked onto each verb and noun. Concentrate instead on the verbs and nouns themselves, and the sensory, physical reality of the characters-in-action in their setting.
2) Too many fancy verbs bumping into each other: yes, a good verb works better than a dull verb spiced up with an adverb, but do give a strong verb the space to run without tripping up on the verb too close in front of it.
3) Too many metaphors/similes/images/figurative language bumping into each other. You may think you wouldn't dream of mixing a metaphor, but you do need to be aware of the metaphorical content of, for example, off-the-peg phrases, or verbs which you're using in a figurative context. You may hardly be aware that they're actually metaphorical themselves - a different metaphor. (My personal aide-memoire for this problem is the glorious phrase that the Worker's Revolutionary Party came out with: "There is an army of strange bedfellows jumping on the bandwagon.") It's particularly disastrous when the physical image in the metaphor clashes with the physical situation on the ground in the story.
4) Too many new coinages and non-standard words. If you make a verb of a word which isn't normally - if your characters carriage their way home or cooking-pot their hatred - then it's a stronger hit than travelling home or nursing hatred, and it needs space round it to breathe. If you have an anglo-saxon attitude to blood-girths and earth-bonds, then give them enough space to work their magic.
5) Every point/emotion/statement/feeling/description is over-laboured, over-worked, over-explained. You're just using too many words for each thing you’re trying to say, like your dotty aunt who can't say anything less than three times, with different details, circling round and round the story in the hope of getting the reaction from you that she wants. How much time and attention any bit of writing takes up should be proportionate to its importance in the story as a whole. And it's not just jokes which are killed by being explained. This is more of a risk with introspection and backstory, and it's not the same as a Henry Jamesian exploration of a mental state, where every sentence actually does lead on to the next in a causal chain, leading us into an ever-deeper understanding. But you have to be a genius to do that well, and most of us aren't. Trust your reader to get it: remember that it's story they found for themselves, between your words, which is the story they'll make their own.
6) Too much Telling - trying to explain and label everything like a teacher - when you could just Show us. See my post here, to think more about Showing and Telling.
7) Too much Showing - giving us a ton of detail and demanding we do the maths - when you could just Tell us. See my post here, for whether you're showing too much.
8) The reactions of people – the descriptions of feelings and things - are over the top for the actual seriousness of the event. Don’t make people go scarlet and feel sick and trembly for a minor embarrassment in the shop. And check that you have really conveyed the seriousness of the situation in itself, as part of the structure and nature of the story and the building of the plot, because only then will a big reaction - and the events which follow - be convincing.
9) You never, ever let up with the intense prose, and the intense action. It's not that you should ever stop bothering to think about exactly what word or event should come next. But if your powerful words and powerful scenes are going to get a chance to work properly on the reader, they need time to work, before the reader has the next thing thrown at him/her. Even in thrillers the hero gets a chance to catch his breath and work out who's after him and why, this time, out of range of the enemy; even in romances the heroine shuts herself into her bedroom... and whether the period of quiet reflection is confided to a locked journal, or to Facebook, it's a while before she has to get going again. Humans are built of systole and diastole, as I was exploring here, and fiction must do the same.