Make sure that your principles are not comprised by the funding that you accept: Once you have obtained funding (for example from department of defence or Microsoft) slag off at the weapons trade or the evils of Windows XP at every conference and at every opportunity you have to collaborate.
Promise that you can solve problems that have defeated the brightest minds for a generation; the reviewers will of course be idiots and be taken in.
The key thing is to have a good idea; do not dilute it by explaining it or describing how you will actually do the work.
Do not risk undue criticism by committing to a particular idea or approach; keep it all nice and general.
Do not make the assessors think your idea is too small and simple. For example, just because you really only need a laptop and a top-up stipend for your one graduate student, should not prevent you from asking for $400,000 per year. After all, grants committees always trim budgets.