To all aspiring CTA's - I recently wrote two articles about my CTA review board experience and started to share my study resources in another one. Feel free to have a read - I hope it helps! 

CTA Board experience: https://www.linkedin.com/pulse/how-i-became-certified-technical-architect-jannis-bott-/

Which OAuth flow should I use: https://www.linkedin.com/pulse/salesforce-oauth-which-flow-should-i-use-jannis-bott-/