Today's Shopify tip is a simple one:
Every time you publish a new theme, go through a full checkout.
It sounds too simple but when it catches a checkout-blocking bug just once, you'll be happy you did it.
If you have the time or a team, ideally you'd have a checklist you'd follow to make sure all of the critical areas work.
But start with doing a full checkout.
(And if you haven't done this in awhile, do it now)
If you're not sure what's going on with your sales you can install Repeat Customer Insights to get a better look at your customer behavior over the long-term.