Getting paid on time, every time
Most owners are afraid to ask for money they've already earned. The shops that get paid fast have a system, not better customers.
Invoice the day the work ends
Same-day invoicing gets you paid 7 to 14 days sooner on average. End-of-month batching loses you weeks of cash flow for no reason.
Friendly, automated reminders at 7, 14, and 30 days
Most overdue invoices are honest oversights. A polite reminder closes most of them. Calling a customer a deadbeat at day 35 is the wrong escalation.
Have a real escalation past 60 days
A clear policy (collections, mechanic's lien, small claims) used sparingly is what makes the polite reminders work. Customers who know you'll follow through pay before it gets there.
Take your version of this question further
This is one operator-tested angle on the question. Your shop, your size, your trade, and your team change the answer. Ask your specific version inside Ask a Shop Owner to get a response grounded in how owners like you actually handled it.