You spent all that time figuring out what advertising works for you, and you need to stick to it. (drivingschool.marketing)
In general however, paid and free book advertising works best when it's combined with other marketing, such as blogging and social media, for example. (justwriteabook.com)
Once kids understand how advertising works it provides a bit of protection against the media and gives a sense of empowerment. (sohoparenting.com)