To me, grant-writing is more like a sport than a science. Like any sport, it is a game that richly rewards quick, high-volume producers.
From this perspective, a quick first draft does wonders for your financial success. Sometimes the best thing to do is to write the entire proposal out - from beginning to end - as quickly as possible.
This is what Peter Drucker called the "zero" draft. In this draft, I like to write as quickly as possible while still following all of the funders' directions. This way, I get a good overall picture of the scope of the grant application, and I can identify what exactly the funder really expects from my non-profit client.
Finally, I like to do my research after I have created the first draft...otherwise I just do not know what facts and figures will be really needed to create a credible argument.
In the past, I used to do a lot of reading and internet searching to make sure that I collected all the right information. Unfortunately, I soon realized that 96% of all that data never appeared in the final grant application. Today, I write my conclusions first...and then research only what it takes to make the most credible case for that particular grant.