Not your keys, not your Bitcoins!
Only those who own the private keys ultimately have access to the Bitcoins.
Do not use links to other websites or links in e-mails to websites where you enter your user data (this also applies to e-banking). It is better to enter the address directly in the browser or via Google search. But Google ads could also be fake. Therefore, always use the top search result, which is not an ad, and check the address for abnormalities. As a bare minimum, always check the address in the browser. Never perform software updates for wallets via a link that you receive by email. Always go to the wallet website yourself and download the latest version.
> Do not keep too large amounts on exchanges.
> Adjust wallet usage to the amount you want to keep (large amounts hardware wallets).
> Create backups and keep them safe. Multiple backups are best.
> On a second device, try whether the wallet can be restored from the backup.
> Choose wallet use and backup so that you are still comfortable when the value multiplies.