In one of my email courses about building repeat customers I mention sending handwritten notes to repeat customers to build some trust and loyalty.
Brian sent me a reply to that email:
Great idea for smaller Mom and Pops. However, it isn't scalable when you ship hundreds of orders a day. I agree it is best to not do them at all unless you can truly handwrite them. Maybe we could something like this on our higher priced items where volume is low.
The personalize letter works best at lower sales volume but there are ways to get something similar to work at scale.
One customer sends out a few dozen orders every day and she tries to add something special to each order.
One thing I recommended to her was to get a few packs of fun stickers and use those with her orders. Her brand is quirky and fun so her customers would appreciate the stickers, and it only takes a second or two to add with each order.
It's simple, cheap, and kinda unique.
You could even rotate the types of stickers so it's a new pack each month or week.
Or send one type for the first order a customer places, a different type for the second, etc.
It's not as great as a personal note but it is more unique and human than just a packing slip.
Are your customers disloyal? Do you even know?
Tracking and understanding how many customers come back to your store after their first purchases is critical, though there's hardly any way to find that out with even Shopify's advanced reports.
Repeat Customer Insights can help. With it's Customer Latency Report you'll see how many customers are coming back for repeat orders, and how quickly they come back.