It is a very vague question..like "What clothing suits me ?"
Well.. I can try to answer.

Question - Why do you want to move to cloud. Have you already decided it is Azure (not the competitors like AWS or Google Cloud, which is totally OK. I am a Azure fan. Just wanted to know)

Businesses (sometime business units / specifica application) moves completely/partially to cloud for 2 reasons
- Convert capital expenditure to operation expenditure
- Build solutions or part of solutions that are scalable, available and reliable without breaking the bank.

How to Prep
- Answer varies based on if you are a IT Boutique shop, Enterprise IT solution provider or a Non-IT business with IT teams.

If you can be little more specific, may be we can chat and find a way through it...

First question to ask: Why move to the cloud? Finantial, Support problems? Maintainance of on premises infrastructure? When you answer these questions, and you find a need for your business to move to the cloud, the transition depends on the size of the business and the aplications you use.