Using Retargeting to Get the Most Out of Your Ad Dollars

Other things to keep in mind are that you don't want to show too many impressions, as it will increase the likelihood of "creeping out" your customer. On the other hand, you don't want too few impressions either — the number that's widely used as a guideline is 17 impressions to 20 impressions per user per month. Additionally, you'll want to identify the behavioral segments that you want to plan your campaign around and then test those ads and emails.