Ensure quick feedback to your customers. Ensure your feedback fully hopes to satisfy client needs. Only accept the jobs you can handle. Also, keep in touch with your clients. Inquire about upcoming projects. Above all, ensure that your work always meet the clients need fully. Let client leap great work from you. You can be sure they will always come back any tie!
If you mean to send them messages after the work is completed, without them initiating a new conversation first, that’s considered spamming on Fiverr. It could get you an account warning, and, if you keep doing it, it could get you banned.