To manage multiple Facebook ad accounts as an agency, set up Business Manager correctly by adding client Pages and Ad Accounts under their own sections. Use Go High Level (GHL) for automation and CRM integration. Ensure each client has their own Facebook Pixel for accurate tracking and retargeting tied to their specific website. For billing, you can assign separate payment methods per client or handle payments centrally based on your agreements. Tutorials on this are available on YouTube for step-by-step guidance. All the best @Aaron Goodman