What is the best methods to protect altcoin from hacker?
take care of your private key, passwords and dont click any suspicious link that has been sent to you through pm, shared on any social media sites, etc. the only reason why hackers have the access on your account is because they successfully get your key.
And also check the link because there are some wallet link that are fisher of your private keys and you can't notice it because it contain some one letter added.
Don't also use your account to some games or any investment site that you will open your account on that site and not you send to the address that they need.
Try to have more wallet because there are some hackers on the wallet then when they got your wallet that contains all of your money then goodbye money, unlike you have more wallet and it divides of many token, it surely can't damage all of yours because even you are too careful on your wallet, they can open it but it is too hard.