Prioritize measurable capabilities: throughput (orders/hour), SLA adherence, inventory accuracy, technology (WMS integrations and EDI/API), carrier connectivity, and value‑added services (kitting, returns). Compare lead times, minimums, and pricing models to align total landed cost with service targets.

Carrier access affects transit times and cost-to-serve. Evaluate a 3PL's relationships with ocean carriers, national trucking lines, and last‑mile couriers, plus proximity to ports/highways. Strong multimodal connectivity enables consolidation, cross-docking, and lower per‑unit transport costs.

Key tech includes a modern WMS with real-time inventory, API or EDI connectivity to your OMS/ERP, barcode/RFID support, and reporting dashboards for KPIs. Confirm how the 3PL handles order routing, batch picking, and returns to ensure seamless omnichannel execution.

Negotiate volume tiers, minimums, variable pricing for seasonality, clear SLA penalties/rewards, liability and insurance terms, and exit/transition clauses. Include onboarding milestones, data ownership, and a roadmap for capacity increases to reduce operational disruption as you scale.