This is how I went about creating a success message applying UX principles that I learned from my certifications:

• Congratulated and encouraged the user by saying 'Great Job!'. Added a friendly image to accompany the success message as well.

• Also, a quick recap of the items the user just purchased as good microcopy needs to be useful too. The text "5 other items" is clickable as well and can be used to view the other items purchased.

• Added a 'View Order' button which upon clicking will let the user view their complete order details and track the order as well.

I didn't look for any references for this one and based the design on the countless checkout pages living rent-free in my head.

How I addressed the feedback I received to improve the
design and copy:

• The copy was changed to be more appropriate and helpful.

• Removed the redundant word "successfully" and changed it to just "You've ordered".

• Slightly adjusted the copy to mention the last delivery date possible and thus eliminated any future disappointment. The parcel would almost always arrive before this date which would actually be a pleasant surprise for the customer.

This is a known tactic that Amazon uses as well in their post-checkout message. By providing the latest delivery date, the customer's expectations will most likely exceed when the parcel arrives a couple of days before the mentioned date and gives the illusion of an early delivery.