Prioritize proximity to end customers and major carrier hubs, dock door and staging capacity, WMS and API integration options, flexible labor pools, and the 3PL’s experience with your channel (eCommerce vs B2B). Also evaluate transit times, inbound receiving throughput, and reverse logistics capabilities to ensure SLAs can be met.

Request a detailed rate card and sample invoices covering inbound receiving, storage (by pallet and cubic), pick/pack, kitting, returns processing, and outbound accessorials. Ask about minimums, onboarding fees, chargeback policies, and annual rate escalators, then model total cost per order across expected volumes and SKU profiles.

Require regular reporting on order accuracy, on‑time shipments, inventory accuracy, dock‑to‑stock lead time, cycle counts, returns processing time, and carrier on‑time metrics. Agree on SLA thresholds and reporting cadence so corrective actions and continuous improvement plans can be tracked.

Access to regional interstates, parcel hubs, and LTL centers reduces zone counts and transit days, enabling lower last‑mile costs and expanded same/next‑day service. 3PLs with established carrier pools and cross‑dock capabilities can consolidate flows and optimize routing for faster delivery windows.

Establish a phased onboarding plan with clear milestones: systems integration (WMS/EDI/API), mapped SOPs, labeling and packaging standards, pilot order runs, team training, and performance validation. Define escalation paths and a post‑go‑live support window to resolve operational issues quickly.