Of the many articles and posts I read about how to approach the engagement of customers through mobile devises, this seems to me the smartest one as it summarizes in 4 simple and short points the killer drivers of engagement.
Of the 4 steps approach (which can be by itself improved) I particularly like the second step, as I consider it fundamental. Here it is.
"Develop and learn from prototypes 
Different messages will influence different audiences. Consider using focus groups, A-B testing and other methodologies to test and validate solution"
More than in other channels, given the peculiarity of the customer experience (being on the go, with a small screen, probably in a multi tasking mode, etc.), an effective mobile engagement strategy requires a trial and error approach, especially for those retailers who bet a lot the quality, aesthetics and emotional side of the product, which obviously can't be communicated easily through a mobile. The everlasting problem of on-line look&feel limits becomes even more urgent with mobiles.

Link:
http://www.luxurydaily.com/developing-a-mobile-customer-engagement-plan/