I need advice on best how best I can keep my bitcoin and altcoins .
The best way are the hardware wallets. Lezor Nano and Trezor.
For long term, you can also print a paper wallet and store in a safe. Printing QR code would be easier as you don't need to type your private key.
You can also use portable wallets on a flash drive. For every large amount stored in any of your hardware, it's wise to keep a paper wallet as backup.
You also have the options of dedicated desktop wallet, you can block them from firewall if you don't want to connect for a longer time.
