Some databases offer citation alerts. Each time the article you select is cited you will receive an email notification.
Google Scholar also offers citation alerts.
Some examples are given below.
You can create author and docfument citation alerts in Scopus. Search for either the author or document and then click on the Set Citation Alert link.
You can create citation alerts in Web of Science. Search for document and then click on the Create Citation Alert link.
Once you identify the article of interest, click on the Cited By list.
Click on Create Alert, enter your preferences, and create the alert.