When choosing a Conversion Rate Optimisation (CRO) agency, consider their experience, expertise, and track record. Look for an agency that has a proven record of improving conversion rates for businesses similar to yours. Ask for case studies or client testimonials.

Also, consider their methodology – they should have a structured, data-driven approach to CRO. Communication is also key; they should be able to explain their strategies business goals and processes in a way that you understand.