Show the Flow
Stripe has diagrams of their payment flows, and I think this is really neat. Sometimes it’s difficult to test payment flows without sending a real transaction, and it’s good to know how it works.

They also have accurate email and payment page previews alongside the invoice editor, which is super helpful.
I think more documentation should show the flow like this. A lot of things have step-by-step instructions, but many are missing screenshots and illustrations.
I can read the most descriptive documentation ever written, and try to imagine how it works, but sometimes it won’t click until I see the results. Screenshots help a lot.