1. Is the device containing your wallet connected to the internet or will it be connected to the internet? If yes, go to step 2. If no, go to step 3.
2. Is it encrypted with a secure passphrase? If yes, go to step 3. If no, encrypt it with a secure passphrase and go to step 3.
3. Your wallet is safe to use on trusted devices. Ensure it is in a safe physical location(s).
If the value of the cash in your wallet is greater than that of the bitcoins on your computer, then using the normal passphrase encryption feature of the bitcoin client is probably adequate. this method assumes your system wasn't compromised before the encrypt wallet step, and that there will be no compromise at a later time that includes a keylogger.
if you are worried about protecting larger amounts, only an offline air-gapped wallet is truly secure. when bitcoin gets multisignature then there will be additional methods for securing a wallet.
