1 - convert your private key into your public key and copy your public key onto something that will transfer your public key to an "online computer"
2 - use an online computer to view transactions of the public address/key and to be able to see the unspent inputs of the public key/address
3 - use one of a number of programs/services that can create an unsigned transaction for you
4 - copy the unsigned transaction from step 3 onto a device used in step 1 and copy it back to your offline computer
5 - use your offline computer to sign the transaction in step 4
6 - transfer the now-signed transaction back to your online computer and push it to the network
It would be nice if steps 4 and 6 could be done using QR codes and the built-in cameras most mobile computers have. Using other convenient methods such as USB drives might prove to be risky.
check out the app Bither. There is an app for both Android and iOS. When you first open the app it makes you choose hot or cold wallet. It allows you to use 2 phones, one as cold storage, and sign the transactions with qr codes.