I know, right? It's much easier to write quickly and abundantly than it is to be concise.
But this can be a big problem when you need to stick to a word count.
I usually find it's better to just get it all out on paper (I'll never stop recommending that you take a dump). Then it's time to cut.
I use a system that starts at the macro and moves to the micro. By the time I've made the micro cuts, I'm usually within the word limit.
Three Steps to Cut Your Paper Down to Size
1. Slash redundant sections
The most efficient way to cut down a lengthy document is to cut out entire sections or paragraphs. Zoom out from your paper and examine the argument you're making. Are you repeating yourself? Are there ways to condense a couple of paragraphs into a single one? This is macro-level cutting and obviously not for the faint of heart, but it works. If you're worried, cut and paste the offending sections into a separate 'parking lot' document. You can always review it and add sections back later.
2. Cut repetitive sentences
Sometimes we say the same thing in different ways. Once you've done the macro-level cutting, the next stage is to eliminate repetitive sentences. They can hide within a single paragraph or throughout a paper. Be vigilant!
3. Eliminate wordiness
It might not seem like you can do any substantial cutting by getting rid of single words, but you'd be surprised at how often we double up on adjectives or use the more complex way of saying something. Take a close look at individual sentences and see where you can eliminate wordiness. This is especially effective when you're editing abstracts. I once cut 50 words from an abstract and no one could tell what I'd removed. All I did was get rid of the extras.
What do you think? How will this system work for you? Let me know in the comments!