The safest way to keep bitcoin are;
1.Desktop wallet.
2.Paper wallet.
3. physical coin
4. Hardware wallet
I've been using desktop wallet that is bitcoin core and everything is always safe and never found any problems, the most important thing is to make sure the computer is clean and healthy and always backup.
Don't forget to have a trusted antivirus software or learn the knowledge about how to hacker access to your computer. The easiest way to keep your Bitcoin safe when you using desktop wallet is turn of internet for this computer or hardrive disk store Bitcoin. Until you need to use Bitcoin, you just need to sync new data from Bitcoin blockchain in fresh computer.