To sell personalized products on Shopify I recommend using the App “Product Customizer”
It’s affordable at $5.99 per month and will let you configure an endless amount of options for your users to select when on a product detail page. Make sure you don’t overwhelm them and keep it simple.
Just make sure you take a backup of your site before you hit the install button. I installed this on a recent project and for some reason the /asset files did not update. The backup I took with Shopify’s backup functionality was a life saver.
Bottom Line: You’re only as good as your most recent back up