1) Keep the majority of your coins on an offline machine and only boot it when you need to use them.
2) Split the coins across several different devices (e.g. desktop wallet, mobile wallets) and make sure to use 2FA and encryption where available.
Another way to keep your coins from being stolen is to use a cold storage wallet. While they are not a convenient solution for spending bitcoins, they are a great way to keep your coins safe. With the cold storage keys being generated offline, there is no way for a hacker to get said keys. But when you want to spend the coins on the cold wallet, you have to upload all the coins in the address as the private key is now possibly compromised.
If you want to save coins for the long term, a cold storage wallet is definitely the solution to go with.
So please don't get know anyone about your private key.