From our experience, you don't need the most basic demographic information on the UP, such as age, sex, residence. Focus on their characteristics, attributes, motivations, and their background.
If you have more than one UPs, attach some percentage weight labels to them, such as 10%, 50%, 40%, so you always keep in mind their importance.
Also, you need to know that the actors (UPs) are not only customers. You have to remember that there are members of your client's organization on the other side of your digital product, who often use it through a dashboard - that's why you also need to hear them out.
Also, try to figure out what are the key actor's goals? Do they align with your client's business goals? That's the essence of your client's business model and the UX design. Usually, these goals are totally different, but it's good to check and ask. For example: Would you trade your data in order to have this service for free?
OK, now you are ready to learn how to build your first User Journey Mapping!
