I usually don’t try using coupons since many of the codes shown on websites don’t work, but I feel bad for not trying hard or smart enough. I’ve heard good things about Retailmenot, I haven’t tried it yet but I wondering if there are privacy trade-offs.
Sometimes codes have worked for me, so I’ve certainly saved a few bucks. They probably just track IP, I guess; I can tolerate that. RetailMeNot is no longer a leader in my experience since there are so many other websites that have followed its style; I just now search, “X promo code,” where X = the name of the company providing the good or service in question, and try the first few links.
You can always follow me in using something like NoScript to block all website scripts, and then guess at which ones to try to whitelist in the hopes of unveiling the code with minimal data leakage otherwise. Close any popups immediately.