Sending a painting invoice after successfully completing the job is the recommended practice. You can send an invoice within 24 to 48 hours of finishing the painting project. You can also send the client a receipt for their records showing that the bill is paid. Build a lasting relationship with the client by sending a friendly, follow-up email. You can simply inform the customer that the job is done and ask them if they are satisfied with the results. If the client is happy, you can send your professionally made painting invoice through email.  After receiving the full payment, nurture your customer relationship by sending a thank-you email. This will show that you provide excellent customer service even after completing the job. Satisfied clients will definitely recommend you to their friends, driving more leads and sales to your painting business.  Ask for an online review that you can post on your painting website. Your customers can also directly give your company a review on your Facebook business page, Yelp, NextDoor, and other online avenues.