No Quid and No Quo
I really like this post by Seth Godin about not adopting a quid pro quo approach in marketing.
[With regard to a related subject, our firm decided years ago to stay away from referral fees because they inject a financial incentive into a referral. Our view is if we recommend another firm to a client, it is because we believe that firm is a good match for the client's needs. That approach makes things much easier.]