From What Makes a Good Policy Brief (Lewis, 2009), the best policy briefs:
Are short, which pretty much goes without saying, and also a little repetitive, because policymakers may just scan the page, so you want them to have multiple opportunities to notice your best points.
Use common terms, spell out every acronym, and are in general highly accessible to people who are not familiar at all with the policy issue. Policy briefs are primarily used by those with relatively little context or additional information, so they need to be able to stand alone.
Address a social problem. You don’t need to state that the world will come to an end if your policy isn’t adopted, but you need enough research to tell a convincing story about why change is needed.
Clearly state a policy preference, and why it is the best solution to the problem (as outlined). Social workers sometimes try to play too nice, and to give too much credence to every possible alternative, as though there were no really bad ideas. Of course, there are plenty of bad ideas, and too many of them are making their way into law! Say what should be done about the problem, and clearly and persuasively explain why it is the BEST option. If you want to outline, briefly, a couple of the alternatives (and this is a good idea if there are one or more that are ‘catching on’) and why they are inferior, that’s fine, but just don’t backhandedly advocate for those alternatives. If you think people will have trouble figuring out which policy choice you’re for, then only talk about yours.
When in doubt, cite. Everything that’s even somewhat questionable should be cited, and make sure that you’re using reputable sources; it might be a good idea to have someone a bit neutral look at your sources to give you this opinion (Lewis, 2009, par. 4-8).
For instructions on writing a policy brief and samples, see the following websites: