Without breaking the NDA, I think I can give you the following tips for success in the ECMS:
#1) There are good practice test questions threads that were shared by a Meraki employee. You can definitely use those as a prep resource. I also did the "Cisco Meraki Network Engineer: Fundamental" learning path that is available on the Community. There are practice type questions sprinkled throughout that training that will be very helpful to you. Lastly, I read the "Cisco Meraki Fundamentals" book that was released earlier this year. All three of those were extremely helpful in my prep.
#1a). I also made extensive use of the Intro to the Cisco Meraki Platform - Instant Demo on Cisco dCloud. Since I had left my professional position before I started studying for the test, it allowed me to refresh my knowledge of Dashboard across the entire Meraki product line.
#2) With any technology certification, it's not just knowing the answer, but having an understanding of the why behind the answer. It's more important to have an excellent working knowledge of the dashboard and the overall concept of each product line than very specific model level data. I was lucky enough to have deployed a nearly full-stack Meraki environment over a few years (Cameras came first, then Switches, Firewalls, APs, and a few sensors came last). Our environment also had a non-Meraki MDM, and much of what I learned with that applied to Meraki (some of the vocabulary might have been different, but the basics all applied).
The test is by no means easy, but with the right experience and the right preparation, it is definitely passable. Best of luck to you!
