The commands that change a filesystem are the ones you should be most careful with, and the ones most worth automating. cp copies, mv moves, mkdir makes folders, and rm removes. Only one of those four is destructive, and knowing which one is the whole point.
About 2 min of reading
Preview before removing.
Create throwaway files
Before you run it, say out loud what it will print. Then open the answer.
Preview the glob
Before you run it, say out loud what it will print. Then open the answer.
Remove only those
Before you run it, say out loud what it will print. Then open the answer.
Unquoted names break on spaces and on characters like * and ?. Quoting is one keystroke that removes a whole class of failure, and it is the reason scripts that skip quoting are quietly wrong on half the files they touch.
A command that names the files it touches can be reviewed. A command with a wildcard has to be reasoned about, and reasoning about a glob under time pressure is where the wrong files get removed.
mkdir -p out/ then write into out/. Writing to a folder that does not exist fails with a message that names the folder, which is a good failure. Creating first makes the intent visible in the command history.
mv a b replaces b with no warning. If b was the file you meant to keep, it is gone. Use mv -i for an interactive prompt in a terminal, and check the target exists before an overwrite in a script.
Recursive removal has no undo. The protection is not a flag, it is running ls on the same glob first and confirming the list. Make that habit before you ever type rm with a wildcard.
Each one is defined here on this site. Open the entry for the full definition and the other words it points at.