Connecting with website visitors after they have left your pages is certainly a powerful tool in digital marketing. And while consumers today are more aware of "cookie" tactics, and we might say they benefit by receiving reminders that are relevant to their interests, there is always a tipping point at which retargeting ads may be too frequent and annoying. At that point they are doing more harm than good for your brand. Here are some guidelines for keeping your program safely inside that line and not wasting impressions.