Security of paper/software wallet and threats

[darecky]

I want to store my IOTA/LSK/XMR/ADA on paper wallets or some perhaps on software wallet.

Can you tell me what are the threats of paper wallets, what concerns me are: viruses that can steal your private key/take a screenshot of your QR code.
Regarding hardware wallets your wallet.dat can be compromised, so it's best to encrypt your computer. And you need to backup your seed, isn't it?
I have Ledger Nano S but coins that I mentioned aren't supported yet.

General tips about security of storing your money on paper wallet.

[Paradoxall]

Paper wallet with clean computer is unbreakable. Just buy a device and use it for nothing else except trades and wallets.