Before installing: check the source reputation, verify the download completed fully, and avoid files shared through random redirects.
After installing: review permissions carefully. If an app requests permissions that do not match its purpose, uninstall and re-check the source.
Keep a copy of the installer only if you trust the source and need it for reinstalling; otherwise delete the APK after successful installation.
APK Download – What to Check
An APK is the Android package used to install an app outside a store. It is important to verify you are downloading the real package and not a modified file.