Man...the CFI ride. This is one ride that I would say there is NO one area you can really focus on and there is no way you can be too prepared.
I had my Jepp commercial manual and Rod Machados private manual (if you dont have this, you need it) and the FARs.
I studied for probably 3 hours per night every single night for around 3 weeks plus. I went through all the gouges I had for every checkride up until that point and then made sure that I knew the answer to every question and could teach it. After I thought I knew all that I would need to know I hung out at the flight school every day for a week and would have all the CFIs fire questions at me and I would teach non pilots subjects until they understood it. If you can teach the girl who answers the phones VMC and make her understand it then you can teach a pilot.
Now, you will NEVER know everything but you will be expected to know where to find EVERYTHING. I tabbed everything I thought was important in the FARs and then I also tabbed my commercial manual and the Machado book. The biggest item here is that you can use any resource you want during the oral but here is the catch you need to tell yourself...it is REFERENCE material not RESEARCH material. You need to know right where to find it in a timely manner, not thumb through the glossary and then read it to them.
As for the flying..that is the least of your worries and is by far the most simple task of the ride. It should have started during your commercial. A good CFI will have their student teaching and explaining the process of every maneuver they do so that way when they get to the CFI ride it is old hat and they have been doing it for a while now. Dont forget to always be able to name 3 common mistakes of every maneuver.
Sorry but there is no easy way around this...make around 300 flash cards and study for many hours every night until you make yourself sick...it will pay off in the end. The CFI ride is absolutely not difficult to pass on the first attempt, you get out of it what you put into it.
My oral started at the FSDO at 8am, we broke for lunch at 11 till 12 and then started back up and went until they closed. Mine was a bit excessive but I would plan on at least 5 hours for the oral.