Prioritize demonstrated throughput for peak volumes, technology compatibility (WMS and EDI/API), multi-temperature capacity if required, carrier connectivity for final-mile and regional freight, SLA commitments for order accuracy and cut-off times, and scalability clauses in the contract to add slotting or services as demand grows.

Carrier access dictates available service levels and cost: proximity to main highways reduces linehaul time and supports next-day to 2‑day windows to major markets. Evaluate LTL and parcel pickup schedules, hub connections, and typical transit days to key customer clusters when modeling delivery promises and inventory placement.

Look for an enterprise WMS with real-time inventory, barcode/RFID scanning, lot and expiry tracking for perishables, integrated returns management, and APIs for order orchestration. Confirm KPIs for inventory accuracy, pick accuracy, and reconciliation processes for seller-managed SKUs versus 3PL-managed inventory.

Negotiate clearly defined pick/pack and storage rates, fuel and accessorial pass-throughs, minimum volume commitments, rate review windows, penalties for service failures, and volume tier discounts. Also confirm billing cadence, audit rights, and a defined scope for any inbound receiving charges to avoid surprise fees.

Onboarding commonly runs 8–12 weeks depending on complexity. Milestones should include systems integration and testing, EDI/API order flows, SKU mapping and master data transfer, test order processing and returns trials, staff training, and a phased go-live with parallel processing to validate SLAs before full cutover.