I've told you before that I want to go into scientific communication. One of the things I am trying to do more and more is to work on my editing abilities and for now the chance to do so comes by reading other people's article drafts.
Having people read your work, especially when it's not fully ready to go out can be terrifying, but it's a necessity for several reasons. The main one is that after a while we are so comfortable with our ideas and what we want to say that we see it perfectly explained in paper, but that might not be the case. Is the sentence explaining your model too heavy in words? Do you go around your point 5 times without realizing it? Getting someone outside of your project (or outside of your lab if possible) and tell you if your point got across, is vital. We often lose perspective with our own work; we've worked on this for so long that everything seems evident. But it might not be. For this, I would always recommend someone with a similar (not the same) background though, since it is probably your ultimate public.
Another reason is spelling. Now, a lot of people might get confident on the fact that Word (or whichever word processor you use) has a built in Spelling & Grammar review. However, what I often find both on my writing and in other people's writing is that the sentence is properly spelled and even makes sense grammatically but it's just not appropriate for what you meant to say. This can happen because of a lack of parallelism in the tenses or simple things as forgetting one word. Once again, a fresh pair of eyes might catch those.
While everyone has their own writing style, one thing that is very common in scientific, or rather academic writing, is that we write very heavy sentences. We already have to use a lot of jargon, but sometimes there are simpler structures to use, without losing quality. We also have a tendency to use very flowery language. A friend recently pointed out that no one really uses words such as "furthermore" in daily basis. That might be true, but I think the flowery part is here to stay for a while longer in academic communications. That said, there is no need to over adorn your writing. Once again, having an outsider read your draft might point out those parts where you got a bit too creative with your descriptions.
On the other hand, offering to proof a friend's draft might also help you, if you want to improve your writing style. Just learning new terminology will be an added bonus, and the more you proof, the easier it will be to notice flaws, both on your documents and in other people's.