Depending on where you need the help, you may need to use an app for help with Shipping. For the fulfillment (label printing), you could try something like Shipstation or Shippo in order to automate the order processing and label printing. If you're looking for calculating the right shipping price at checkout (customer facing), you could set up your shipping rates through Intuitive Shipping so that you're always charging the right amount at checkout.
This way, you're always charging and paying the right amount for orders, making your profits more consistent. Hope this helps!
In case you are using FedEx for handling shipping, the Shopify FedEx app would be the perfect solution for you. With the app, you can automate the packing process based on the product weight, product dimensions or you can even pack each of your items individually. You can also create custom boxes of your choice. Labels can be generated based on the number of boxes to be shipped.