One thing I've seen past success with is testing out a message with a small subset of users and adjusting prior to blasting your entire database. Same could be done for emails, ads, landing pages, etc.
For a quick example of email: send an a/b test email to 300 people. See the results, then depending on what you find 'wins' continuing that message to the broader group of 10,000.
For websites it is rather easy to use the free version of Optimizely for this to show 10% of your traffic one thing vs the remaining 90% (depending on how much traffic you get to make it statistically relevant).
If it's more for your overall messaging and positioning then I really like Tamara Mendelsohn from Eventbrite's approach. It goes at it in a pretty pragmatic way across surveys and digital channels - https://blog.kissmetrics.com/how-eventbrite-built-scaled-their-marketing/