For starters, miranda. Imho, minors are not in a position to waive miranda. Thus, by default, they should be appointed an attorney before *any* questioning can begin.
In addition to the presence of an attorney, I strongly lean towards having a GAL (guardian ad litem), involved. This should, hopefully, reduce the sort of thing we witnessed with Brendan and his court appointed attorney, Kachinsky.
I would also support mandatory competency hearings for juveniles who are being tried as adults. That is, do they understand the charges and can they assist in their defense?
And finally, though equally, if not more, important. LEOs need to be trained with regard to questioning minors in order to avoid false confessions as well as false accusations. Why? Abominable interview techniques is how we ended up with the daycare scandals that swept the nation back in the late 80s to early 90s.