Developing effective strategies and methods for finding suitable funding opportunities takes time, practice and patience.
Don’t judge a "not-fund" as a failure. Try not to take it personally: the funding environment is competitive, and many excellent proposals aren't funded simply because the funds aren’t available to fund them all. And, truth is, some luck is involved! (Eg; Lead reviewer may not be in the same field.)
Review, Revise, and Re-Submit!
Pay careful attention to reviewer’s comments, and address their concerns in your resubmission.