Many parents have asked me where they can get guidelines for MLA and APA formatting. Here are two websites that have easy to follow guide lines for both.
There are also books on Amazon and at Barnes and Noble that are easy to follow and would be helpful in understanding formatting. Having a book on formatting with you at all times makes for an easy reference.
I suggest you begin teaching a specified format around 6th grade. I used MLA, but I think that either MLA or ABA is fine, because once a student learns one type of formatting it is easy to switch to another if it is required.