1 – What are the objectives (How Data can help me to…)
2 – Define my goals vs the objectives (which KPI I want to improve)

3 – How (my strategy)

4 – Measure your data maturity (compare to your competitors)

A list of sources to read
Data Strategy by Bernard Marr :
https://www.bernardmarr.com/default.asp?contentID=660
Where the focus is on taking better business decisions, improve your business operations and monetizing your data
The role of Data Strategy in the Digital Transformation Journey
https://link.medium.com/KDmdWobfv7
A vey good article on the most important areas to cover by your data strategy : customer experience, people, process, new value propositions and innovation
The 4 levels of analytics
https://www.kdnuggets.com/2017/07/4-types-data-analytics.html
Because it is key to know where you are and which level you want to reach
Gartner Data Strategy definition
https://www.gartner.com/en/documents/3975595/creating-a-data-strategy
Just an access to the chapters but a very detailed plan. The previous articles and the schema are more focus on the why and what.
Another gem : Do you really have a data strategy ?
https://towardsdatascience.com/do-you-really-have-a-data-strategy-ff08795f10ce