When comparing agents, ask about their experience with your specific product category (food, electronics, vehicles and hazardous goods each carry different complexity), their typical clearance time at Douala versus Kribi, how they charge (a flat fee, a percentage of shipment value, or itemised per service), and whether their quote includes or excludes disbursements such as port storage, ECTN fees and inspection charges, which are commonly quoted separately from the agent's own service fee.
Get every fee structure in writing before your first shipment with a new agent, and ask what happens, contractually, if a shipment is delayed or held for reasons outside the agent's control; a professional agent will have a clear, honest answer rather than a vague reassurance.