Leave a link! If you're leaving a message on my talk page about a draft, please ensure you link to it. Preferably use a wikilink e.g. Draft:Example but [1] will suffice as well.
Unless the pre-determined decline message amply explains why I declined your draft, I will usually leave a comment which can be found between the red box and the start of your draft. This should give you a few pointers. If you're still struggling, have a read of this and if you're still confused, leave a message on my talk page.
A quick note: I, along with most other AFC reviewers, do not review drafts upon receiving a request to do so on my talk page. This is to ensure users who don't leave messages aren't disadvantaged, as well as to cut down on the talk page backlog. If you do understand why your draft has been rejected, work on it and re-submit it. If you have re-submitted your draft, please don't notify me because I or another reviewer will look at it in due course.
Another quick note: sometimes my AFC feedback may sound somewhat terse, however I try to review drafts critically because once it enters the mainspace, it will be subject to the entire range of deletion policies and my aim is to help you ensure your draft is in a condition that it won't be subjected to those policies at AFD.