Not sure I can help much in terms of resources - the best ones are definitely successful grants from folks working on somewhat related topics. We had a history passed down through our lab since a lot of people applied. That said - don't feel like they have to be related. A lot of it is about structure, training, etc. and that can come from anyone. I've borrowed table/figure ideas and other little bits and pieces from completely unrelated grants.
Other main piece of advice would be to never count your chickens before they hatch and think about other places you might want to submit. My F31 narrowly missed being funded on its first submission and did WORSE on revision despite my addressing reviewer concerns in what everyone agreed was a reasonable way (turns out it had just gotten sent to different reviewers). Nothing is guaranteed. If there are other organizations where its relevant (I do health psych stuff, so was able to submit to American Heart Association), submit it there concurrently. Its not like papers, its perfectly acceptable to have the same grant under review in 8 different places at the same time.
