I am in the National Guard looking to go AGR. Is there any place where I could find some study sheets for becoming a Unit Training NCO?

If you have FB, Checkout the MILTECH/AGR FB group. There are a lot of individuals with a wealth of knowledge. Most are working S1 and S3.

If you are applying for an open position, call the unit where the opening is and ask the person working there. Most of the time they are willing to help out. Definitely study AFCOS, DTMS, DTS, know your accounting classifications, where to find references in DTMS exact job descriptions will vary

I'd do some data mining on MilSuite