Here are a couple of interesting pointers for submitting an NSF proposal. This is not a comprehensive and complete list, but it does touch upon some of the important features that a proposal should contain.
1- The proposal should not be an abstract, but a self-contained description of the activity if the proposal was funded.
2- broader impacts should be described, which show the implications of advancing this research
3- Details should be understandable to people who are not in the field, but technical enough to convey the importance of the research.