offline wallet is a good place to saving bitcoin but when you need to be active on the market offline wallet is useless, send extra money to offline cold storage and keep remaining amount online. use a safe computer or use secure wallet. you can protect your bitcoin by sms authentication on asmoney.com
Sms authentication is not helping that much. If asmoney is hacked or if its CEO is a scammer or who knows what, your BTC is gone.
This is why only a solution like bitgo is truly secure. Even if bitgo is hacked, hackers cannot access your coins...