1. Only install well-known apps, ones that are extremely popular, from big companies.

Odds are that they have an army of developers behind them and will make fewer mistakes than the small apps from less experienced creators.

2. Do a clean-up among the apps already installed. Get rid of the ones that you don’t use anymore.

3. Also get rid of the ones that require too many permissions (why would a flashlight app need access to your text messages?).

4. Keep those apps up to date. Vendors constantly come with updates that bring new features, but also fix security and privacy vulnerabilities.

5. Install a trustworthy antivirus (again: it should be from a big, well-known vendor).
 

In case everything else falls, you should have an automated backup.

This way, if you ever end up with a malware infection, you’ll have all your important files already saved and won’t regret formatting your phone.