Prioritize measurable KPIs: transit time to key customers, dock-to-stock and order cycle times, pick-and-pack accuracy, and carrier mix. Evaluate technology (WMS/TMS/APIs), value-added services (kitting, returns), slotting flexibility, and scalability to handle seasonality without service degradation.

Closer proximity reduces drayage, shortens lead times, and increases carrier options — lowering variable transport costs and improving on-time performance. For cross-border or inland flows, good highway access reduces transit variability and supports reliable replenishment cycles.

Require a modern WMS with real-time inventory, standard API connectivity to your storefronts and carriers, event-based ETAs, and reporting on SLA adherence. Also ensure the 3PL can support ASN workflows, batch/lot tracking, and returns processing to maintain omnichannel consistency.

Compare total landed costs (storage, handling, inbound/outbound transport, and value-added fees) across volume tiers. Request scenario-based quotes for peak volumes, ask for minimum commitment terms, and assess the provider’s ability to scale labor and racking to avoid sudden cost spikes as demand grows.