**Building is the easy part.** The hard part is refreshing your Stripe dashboard 400 times a day waiting for a notification that never comes. **Your mom signing up doesn't count.** But I'm still counting it. **Validate before you build.** I didn't do this, but I've read it in enough LinkedIn posts to know it's important. So I'm passing it along as original wisdom. **Cold DMs work.** Sent 847 of them. Got 3 replies. Two said "unsubscribe." One said "who is this." T...