PIGEONHOLING
. The Consumers Union points out that it's unnecessary to fill out surveys with warranty cards. Just send in a proof of purchase with your name and address. ''Protecting your privacy is a significant tool to prevent yourself from being pigeonholed as undesirable,'' says Gene Kimmelman, Washington co-director for the CU. It's equally important to recognize what kind of information companies are looking for. If you don't live in an upmarket Zip Code, consider using your work address for correspondence. Be optimistic when estimating your income or spending: The better the numbers look, the better you'll be treated.