Research & recognise diversity
We first need to know our customer. How might their experience of Customer.io vary based upon variables like internet connectivity, geographic location, the education level of the user, language (including slang), their age, their attention span?
For example, understanding how to design for lack of focus or lack of attention will guide us in how much information we can and should present at a given time.
Recommendation: put together a group of customers whose experiences vary wildly in as many variables as possible.