but one should ensure that it is up-to-date and has multiple layers of security.
What do you mean by multiple layers of security? If you mean securing the wallet with 2FA, SMS, email, etc. I wouldn't recommend it.
Your fund is secure as long as you are the only one who has access to your keys.
For keeping the keys secure, you should either use a open-source hardware wallet or a cold wallet created on an airgapped device.
If you do all the steps correctly, you don't need any other thing.