A customer persona is a fictitious representation of your ideal customer. Defining your customer persona usually start by answering these questions about your ideal customer:
How old is your persona?
Where do they live?
What is their occupation?
What motivates them?
What do they like and dislike?
What pain points do they have?
Where do they get their information?
and many more. Extend this as you wish.
There is no right or wrong about creating your customer persona. What you always should include are the pains, gains and jobs that related to your product or service as well as the emotions attached to those.
Include demographics, psychographics, sociographics if you think you can pin your ideal customer down using those characteristics. In our experience this is in 50% of the cases impossible.
This is a good exercise but keep in mind what you are usually doing is theory. You need to confirm your customer persona hypotheses. We will explain later on.