Google has a few suggestions. According to Google, you should always enable Play Protect. To do this, go to the Play Store, click on the profile icon, and then go to the Settings option. From there you can then scan all the apps on your phone. 

If an app looks harmful, uninstall it immediately. Phone software should always be kept up to date. The phone's security system has been strengthened. Apps should not be downloaded from any platform other than the Google Play Store. 

The trend of downloading APK files on smartphones should stop. Before visiting a website in Chrome, turn on your browser's Settings > Privacy > Safe Browsing option.