Securing your SmartCash QT wallet is as important as securing the physical wallet.
Same principles apply but with SmartCash QT wallet more attack vectors are present.
Because of it, it is more important to pay attention to securing your funds against attackers and malicious software.
Password Protection
Every single SmartCash QT wallet should be encrypted with a strong password!
Encrypting the wallet means that the data file holding private keys (such as SmartCash QT's wallet.dat) is not readable by default.
When the file gets stolen the attacker can't easily extract keys and spend your SmartCash.
He'd need to brute force the file which takes a lot of time - thus the importance of a strong password. It should be reasonably long (at least 16 chars) and comprises of numbers, lowercase, uppercase and special characters.
Click here and here for more info on strong passwords.
Store smaller Amounts
As with your physical wallet, you shouldn't have all eggs in one basket.
It's a good practice to load your regular mobile/computer wallet with smaller amounts and replenish it when needed. The rest should be kept somewhere secure in a cold storage. (SmartCash are working with some cold storage provider to support SmartCash)
Keep it Up to Date
Every software has bugs and SmartCash QT wallets are no exception.
Make sure to check for updates regularly as they bring new features and most importantly security and stability fixes.
You should use modern operating systems such as Linux, Mac OS X, iOS and Android to keep your software updated automatically.
Backup
Always backup your wallet and store it in a safe place.
It prevents you from losing your SmartCash in a case of a hardware and software failure. It also lets you recover funds after your PC or mobile was stolen or lost.