When a new request comes for membership into the KID group, these are some good practices that I've put together based on rdk1 and thordura, and from reading the various forums in KID and KID Admin.

Visit the user's profile to vet them. Look for family-friendly avatar, no evidence of cheating, etc. Ideally they've been on chess.com for 3+ months and have played many games, and possibly posted on forums, etc. < 3 months may be OK if they've shown significant activity and you can track their comments on other forums, etc.
If vetted, go ahead and add them, and then send them a personal message with content shown below.
Post a message on the KID Group home page, welcoming the new member: "Welcome New Member X!"

DIRECT MESSAGE TO NEW MEMBERS

Subject: Welcome to King's Indian Defense!

Body: Welcome to King's Indian Defense! Feel free to join our vote chess games in progress, but please see our group forums for helpful information and guidance, especially "Welcome to the King's Indian Defense" and "Team Vote Chess Guidelines." Useful links:

KID Group Page

https://www.chess.com/groups/home/kings-indian-defense

Welcome to the King's Indian Defense Forum:

https://www.chess.com/groups/forumview/welcome-to-the-kings-indian-defense

Team Vote Chess Guidelines:

https://www.chess.com/groups/forumview/team-vote-chess-guidelines8

KID Admins

Super Admins