I'm currently working on my Commercial cert. and will start preparing for my CFI quite soon. In everyone's expert opinion, what's the best study material you can buy for the CFI? I've been using the Jeppesen kits for the Private, Instrument, & Commercial and they've been working out great. I just need to know what the best material out there is to prepare for the written tests as well as the oral portion or "lesson plans" for the instructor. Thanks.