Consider using a false name, age, phone number, etc. Don't use your personal email, use a separate one . Submitting any of this information may reveal your email address as well. Of particular concern to parents are sites that do appeal to children, and ask kids to submit additional detail such as their age, hobbies, or number of siblings. That kind of information should be guarded as closely whether asked by a web site or a stranger on the telephone.
Cookies are the latest hot privacy potato.
Cookies are small, cryptic text files that are put on your computer by web site operators who want to track your movement through their site with more detail and over a longer period of time. They were designed and implemented by the engineers who created the world wide web, and are intended to make the Internet a bit more useful. By themselves, cookies do not contain any personally identifiable information about you. For the truly paranoid, cookies are feared because theoretically they could be directly associated and combined with other information databases that do contain personal information about you, thus providing a fairly detailed profile of your interests and buying habits on the Internet. Current use of cookies is employed almost exclusively by large commercial sites, and they cannot be read by any computer other than the one that put the cookie there in the first place.