Andrew Gelman has a good article called Advice on writing research articles - Statistical Modeling, Causal Inference, and Social Science.
I am thinking about printing this out and giving it to my graduate (and maybe undergraduate) students. Here are his main items:
1. Start with the conclusions. Write a couple pages on what you've found and what you recommend. In writing these conclusions, you should also be writing some of the introduction, in that you'll need to give enough background so that general readers can understand what you're talking about and why they should care. But you want to start with the conclusions, because that will determine what sort of background information you'll need to give.
2. Now step back. What is the principal evidence for your conclusions? Make some graphs and pull out some key numbers that represent your research findings which back up your claims.
3. Back one more step, now. What are the methods and data you used to obtain your research findings.
4. Now go back and write the literature review and the introduction.
5. Moving forward one last time: go to your results and conclusions and give alternative explanations. Why might you be wrong? What are the limits of applicability of your findings? What future research would be appropriate to follow up on these loose ends?
6. Write the abstract. An easy way to start is to take the first sentence from each of the first five paragraphs of the article. This probably won't be quite right, but I bet it will be close to what you need.
7. Give the article to a friend, ask him or her to spend 15 minutes looking at it, then ask what they think your message was, and what evidence you have for it. Your friend should read the article as a potential consumer, not as a critic. You can find typos on your own time, but you need somebody else's eyes to get a sense of the message you're sending.