The best way is to write your keypairs to paper and put it in the safe.

One of the unsafest ways to handle your keypairs, is to handle them in a wallet on your own Computer!!!

yeah, you may smile now. but thats a fact.

did you ever lost your images because of a hardware-crash of your end-consumer samsung HDD? i did.
if that happens to your wallet-PC (and you did not write down the keypairs before) all your coins are all gone forever.
even if you backup your wallet-dat at external HDD and USB-Sticks. Maybe there are dead in 10 Years. even if you run a RAID, your are never sure.

if you handle your keys with a BIP 39 Wallet (every deterministic wallets, must not be coinomi) you can recover all your keypairs if you just remember the recovery phrase (write it down, don't store it at a digital device).

there is nothing unsecure about that at all. and you need to thrust no one. all that calculations happen on your device only.