Mechanical Details Take care of the administrative details. Don't give someone the opportunity to dismiss your proposal because you failed to follow instructions. Be sure you qualify. Many programs, particularly at NSF, which have no official deadlines, are more likely to be funded if the reviews of your proposal are complete and the project is ready to be funded early in the fiscal year before all the money in the program budget is committed to other projects. Instructions - Make sure your proposal incorporates all requested information.
Readability is important Reviewing proposals is a tedious job.
Put yourself in the reviewer's shoes and do what you can to make it easier. The physical appearance of your proposal is often used by the reviewers to judge your scientific ability. A sloppy proposal may be taken to indicate that your science may also be sloppy. Spend the time to make a good summary of the proposal. Particularly in a panel review process, the summary may be all that some reviewers will have time to read.