Well your wallet is where you keep your coin safe and it always important to protect it
One of the best way is to protect your private key never give it out to any one even if it's your mentor that is very important
This is for new guys like me
Of course there is no one who want to give their private key to other peoples.
But the problem is, you will need to use the private key when you want to use the wallet for send coin.
This is the flaw of your safety, thats why many peoples recommend using other method than private key to use the wallet.