I didn’t have a checklist. I found that when I was speaking to the client the conversations flowed, I wrote a few questions down that would help me to find the information that I needed.
What are their challenges? Where do they feel they need support? You will then be able to gauge the next steps. Every client is different but I would have the q’s you would like to ask them, then create an onboarding process that you can follow.
For example, discovery call with client, proposal, send contract etc.
There is also a lot of online support and forums that you can search to help you.