I took the certification exam last week (and passed ), and would advise the following:
General Strategies
Take your time, and set aside at least 3.5 hours from start to finish
Set up in a comfortable, private workspace
Go to the restroom beforehand
Do not underestimate the exam
Exam Strategies
Read + understand the exam and proctoring rules
Know the Bubble manual and documentation inside and out
Have a blank Bubble app with access to backend workflows ready (any app on an agency plan will do)
Use process of elimination and known true/false strategies for multiple-answer questions
Use the Bubble editor for experimentation.
Know how to use the debugger
Focus Areas
Bubble API and API Connector
Data & Workflow APIs
Authentication vs. Authorization
API connections
Backend workflows, including recursive, recurring, and database triggers
Workload unit (WU) optimization comparisons
Privacy rules
Optimized database searches
URL parameters/paths
Some links to the relevant sections of the Bubble manual. It is particularly helpful to be able to make a list of true/false statements about each of the topics.