Try the guys at theprintful.com they have made a good niche business providing the services you seem to be needing. Best of luck, learn from them and keep asking questions ;)

Shipstation is best. It can also extend outside of Shopify to other marketplaces. With that many orders under a pound you may also want to consider DHL eC. They can often beat First Class Mail rates for very small packages.

I would definitely recommend ShipStation for your intended application. ShipStation can cover all your bases. It can quickly assign appropriate carrier / service levels to orders through automation rules, allocate and track inventory, and send customized tracking update emails to your customers. Once you're set up in ShipStation, they can introduce you to high-volume shipping services such as DHL eCommerce which will save you money on shipping.

Let me know if you have any questions!

Here’s a response you could use:

For building out your fulfillment and shipping function, there are several best practices you can follow:

Automation: Implementing software that automates label generation and order processing can save time and reduce errors. Consider integrating with a shipping software that can connect directly to your Shopify store for seamless label creation.

Inventory Management: To keep track of inventory and manage stock levels effectively, you’ll need robust inventory management software. This should provide real-time updates as orders are fulfilled and offer features for tracking and managing your SKUs.

Customer Communication: Ensure that your system can automatically send tracking information to customers. This improves the customer experience and reduces inquiries about order status.

For detailed insights into logistics management systems and how to select the right tools, you might find this article useful: https://www.cleveroad.com/blog/logistics-management-systems/. It covers various aspects of logistics software that can help streamline your fulfillment and shipping processes.

Best of luck with your fulfillment operation!