Preparing device for securely storing wallets

It is very important to protect your device such as laptops or mobile phones in which you would like to store your wallets.

Consider using an air-gapped device (such as a laptop or computer). An air-gapped device is completely offline and does not connect to any network such as internet, bluetooth or wifi. If your device is entirely offline, it is one of the best ways to secure your wallet. After executing transactions, disconnect from the internet and keep it offline.
Consider using a new device to avoid old devices which might have been compromised.
Install an anti-virus software, especially if the device has to be online.
Encrypt your laptop or computer drives using a technology like Bitlocker or VeraCrypt for Windows. For Mac, use FileVault. Even if your device or disk is stolen in the future, the wallets cannot be retrieved. Ensure you keep multiple offline backups of restoration keys.
If you use a memorized password to protect your wallets, ensure you repeat it periodically in your mind (once a day at-least). Consider writing down the password offline and keeping in a safe place. Any password less than 32 characters is a security risk. In general, human generated passwords are not recommended.
Keep a backup of the wallets in at-least 3 different devices and in different geographic locations in a safe place. Ensure the backups are protected with strong passwords.
If you use strong passwords, you may keep the wallets (not applicable to seed phrases) saved on new USB drives and keep them in a safe location offline. Keep atleast 3 copies in different locations.
Do not keep the wallet and password in the same location! This is very important.
Educate your trusted and knowledgeable family members on keeping the devices and offline backups safe.
Do not keep seed phrases or wallet keys saved as a screenshot.