Seven key ingredients that determine whether a message will be passed on by people:
1.) An immediately outstanding story
2.) Stickiness (in people’s minds)
3.) Relevance
4.) Portability (how free the idea is of barriers)
5.) Shareability (how ‘networking cementing’ it is)
6.) Timing/actuality
7.) The hook (the one-liner that grabs your attention)
Advertising Concept Book (Second Edition) by Pete Barry citing The Viral Factory