Everyday, in order to subscribe to certain services on the Internet we are almost forced to disclose private data even though those services don't necessarily require it. For example, I need to expose my credit card number in order to register for iTunes even if I just want to browse through free apps, etc. This seems risky to me and I feel I should only have to provide my banking information on demand.
In most cases, we may face targeted marketing through the private data we disclosed over the Internet.
Are there any guide books or guide lines to know how to prevent exposing our private data to service providers over the Internet when it is not necessary?