Hey, Kelly,
Buy something from me and I'll show you how I do it.....just kidding...lol!
Good question, really.
I put a little note in my invoice area that only the buyer will see at the bottom of your info and appearance page, there is an area listed as message to buyer. I thank them for their purchase, ask them to let me know if they have any problems, questions, suggestions for products and services by sending me a message then follow it with a request for feedback.
Only a few have not done it, so I send them a convo asking if everything was alright and if they needed anything else. After they respond, I ask if they might take a moment to leave me feedback for my shop.
After each feedback, I thank them, tell them that they are welcome back anytime and give them a discount code to use anytime in the future.
I have only received good comments on this approach for both of my shops, so it feels alright to me.
Good luck!
Cocokate