Safe cold storage for beginners

I seem to know more about bitcoin than basically all of my friends and family. They for the most part believe it's make believe, worthless electric money ????. I'm trying to bridge them over to the orange side, but it's a process lol.

I have a ledger cold storage wallet, that has the 24 word auto generated seed phrase from when I set it up. Initially I heard that was the way to go, but occasionally I hear that I'm still looking at the tip of the iceberg with regards to cold storage. What would be the next steps I can take, to make my crypto even more secure than it is now?