i stick with only the 'free samples' ones, you just hit no on any other offer, ( normally it asks if you or someone you know, blah blah blah... just click no or it will redirect you to a totally new page.) and then give it an old email you dont use anymore, so it can flood it with stupid emails you dont really care for, and your address (put a real one, in case they actually do send samples of course) and thats it. :)
some of the free surveys give quite a few, and want very little info, just an fyi. like the ones for free samples, only want an email address, and name. :) and you get like 368 or something like that for a lot of them.