Took my PMI-ACP exam today and here are some advices 
The exam is relatively easy if you cover the outline topics well, and go through the important outline topics using the reference books as follows:
- Focus on XP practices, techniques & roles
- Understand the Value Stream Mapping
- Understand communication, collocated teams, distribured teams and Osmotic communiation
- Understand Lean Portfolio Management
- Understand Estimations using story points and velocity
- Understand information radiators, and focus on burn-down charts, their value and what do they represent.
- Understand Agile manifesto and principles
- Learn about Pareto’s Law
- Learn about Risk management and risk burn-down
The exam questions do not need 3 full hours if you’re well trained, try agileexams.com, its questions are almost of the same complexity
Good Luck all
- Nevine