Except where you need to enter your real information, such as at a financial services site, we may be best off always logging in as a fictitious person.
Create an alternate name and an email address only for online activities. Keep it separate from your regular email address. Also create yet another email address for retailers and other offline activities.
Never, EVER sign in to a web site or app using a Facebook or Google ID – never, ever do that as the moment you do, they are tracking you and spying on you.
By doing this, you may break the chain of spying. However, as shown by researchers, many Android apps harvest the globally unique identifier assigned to every Android phone and are using this to track your device and activities also.