Aviationinterviews lays it all out on the table. They have every possible HR and technical question that could possibly be asked in the Envoy specific interview. You will probably not be asked a question that is not on that website!!!!! Most of the answers to the technical questions are actually there too! Pay the $20 or whatever it was and use that website.

Me personally, before I went to interview I printed out all the questions, made a answer to every possible HR question (because I'm traditionally terrible at hr). I studied the tech questions and read through the jeppesen charts guide. Here's the link.
http://ww1.jeppesen.com/documents/aviation/business/ifr-paper-services/glossary-legends.pdf
On my study breaks/days off I worked on my logbook and got the mountain of paperwork neatly in order.

Did I mention to pay for aviationinterviews? It has half of the answers and all of the exact possible questions you will be asked.

That website is the gouge and there are dozens of actual envoy experiences on there!