Go through Chad's vids, do ALL of the O-chem problems in destroy, and if you get a copy of ORGOMAN's Organic Chemistry Oddyssey, that in itself is very good material! Cover all of it!
I personally went from OC 18 => OC 23 because I did odyssey. You should do it twice over and perhaps supplement it with the roadmaps. Roadmaps only give you basic skeleton structure for OC reactions and mechanisms.
Beware... Questions that will show up in some form or another in the Orgo section of the DAT.
-Diels-Alder
-Grignard
Two questions out of 30 may not seem like much but it will mean the difference of 1-2 points on the OC section!