For organisations looking to migrate workloads or their datacentres from on prem into Azure the first phase of the project is to do a discovery of the environment. And regardless of the size of the organisation or the amount of workloads being moved the discovery phase is really important.
I advocate that every organisation looking to do a workload or datacentre migration should invest real time and staff resources into the discovery part of the project. Understanding your environment, truely finding out how things are connected within your environment, speaking to end users and application owners, and getting your documentation up to date can really help you later in the project and make informed decisions.
Often a question I get asked by customer is, "do you have a checklist of the information we need to collect?" Up until recently the answer was no, however I've now pulled together a checklist to help organisations. The checklist can be found here and as it is hosted in GitHub, if you want to contribute to it you can! I want the checklist to be collaborative, please feel free to make a pull request and add your thoughts as well. 😀