I was primarily talking about browsers because web ads were the concern - and also probably the most common way to be spyed on. But for desktop and mobile I ca

I was primarily talking about browsers because web ads were the concern - and also probably the most common way to be spyed on. But for desktop and mobile I can't endorse enough running a software firewall with outgoing blocking and active prompting - many of these will also let your block things from injecting into other applications, adding themselves to startup, etc. XPrivacy on mobile works wonders. Outpost used to be my recommendation on Windows, but it's unfortunately dead now, so I've been running ZoneAlarm lately, which does a decent job. If someone knows something better, please let me know.