Prioritize measurable KPIs: transit-time reductions, order accuracy, on-time shipments, and inventory turnover. Evaluate WMS/API integrations, pick-and-pack throughput, returns handling, labour stability, and the 3PL's ability to scale racking and throughput for seasonal peaks.

Carrier mix and highway connectivity determine routing efficiency and per-shipment cost. Proximity to main corridors reduces empty miles and drayage to ports; access to LTL consolidators and regional TL carriers improves consolidation economics and reduces landed cost for cross-border shipments.

Look for robust WMS with API/EDI, real-time inventory visibility, batch/zone picking capability, returns processing, temperature-controlled zones if needed, RF/barcode scanning, and SLAs for pick, pack, and ship to support omnichannel flows and customer expectations.

Negotiate clear billing units (per-pallet vs per-cubic), storage tiers, minimum monthly charges, transparent accessorials, volume-based discounts, performance SLAs with penalties, and exit terms. Include audit and reconciliation cadence to avoid billing drift.