Promote new content on your website to your potential customers. Inform them regularly via an email newsletter.
Keep in tocuh with your customers
Inform your customers using an email newsletter about your new products and services. Do it regularly: not too much; determine the optimal frequency. Make sure that you offer good content in your newsletter that your customer can use without having immediate need to purchase a service / product.
There are several options to send newsletters to customers: through a Joomla component or external services. In both cases you can add a registration form on your Joomla website to register names + e-mail addresses.