Hey Jake,
welcome aboard.
I would recommend you to read this articles for a start:
https://forums.envato.com/t/a-customers-guide-to-what-makes-or-breaks-items?source_topic_id=48177
https://forums.envato.com/t/what-are-the-most-commercially-viable-genres-on-audiojungle?source_topic_id=48177
https://forums.envato.com/t/the-top-rejection-reasons-in-the-audiojungle-review-process-and-how-to-avoid-them?source_topic_id=48177
My personal advice is to be consistent and work hard. Try to keep eye on quality not on quantity.