Step 1 Open https://bitaddress.org

Step 2 Right click and save as to your desktop Save as a html file in your downloads folder or any other folder

Step 3 Disconnect Internet

Step 4 Double click and open the saved HTML file in your downloads folder in any internet browser like chrome or firefox The address will be something like this file:///Users/yourusername/Downloads/bitaddress.org.html

Step 5 Randomly move mouse and use some random keystrokes and generate a bitcoin address

Step 6 Take a printout of the private key and the public key with the QR codes

Step 7 Store the printout in multiple locations

Step 8 Use the QR of the Public key to accept bitcoin to your address which was never connected to internet at all

Step 9 Import the old private key to a wallet like Electrum wallet which allows to import private key Spend from that wallet. Repeat Step 1 to Step 8 to transfer the remaining bitcoin to a newly generated wallet.