How to keep your MetaMask wallet 100% safe?

There are many sites we connect our wallets with and approve sign in. How can we make sure the site which is asking for permission to connect wallet is safe and won't let it do any transactions?

Lately there's so much scam going on and, hackers have found new ways like sending free tokens and you know why.

I don't even remember how many sites I have my MetaMask signed in to so I was thinking about creating a new primary wallet while using others  for unauthorized sites.

Please leave your guidelines on how to keep wallets 100% safe, thank you.