Completing Applications for Grant Funding

1) Follow the guidelines. This terribly obvious rule is not followed by many grantseekers.  The most common error is to assume that some parts of the application are less important, or deserve less time and attention, than other parts.   Give the funders what they want in the way they want it.
2) Check for inconsistencies.  Does your abstract accurately describe the project proposed?  Do you request funding in your budget for resources that are listed elsewhere as available?  Are any "key personnel" named without their role described?
3) Maximize clarity.  Make your entire application easy to read, navigate, and understand.  Reviewers are humans as busy as you.  Do not make them struggle with your application.
4) Finish early.  Give yourself enough time to revise, re-revise, check, and re-check.  A day spent thinking about the "finished" product usually produces ideas for improvement.  It helps if the application has not yet been mailed.