It is a vital for any projects to have quick starter guide for new joiners. As part of On-boarding he/she should be given needed support and forum to understand, learn, accustom and perform.
Here's my starter guide index from Jira admin's hat to all new joiners:
And my Trello planning board with the resources made available for project team members:
Please post your comments, ideas, checklist items that can be included to make the onboarding kit more valuable.
Stay safe and stay healthy.