I have a Nexus 4 with Android 4.3 and I am trying to connect the device to a computer with Windows 7 64bit.
I installed the latest drivers and the latest adb>
adb>
After you ensure you have enabled USB debugging unlock your phone and plug it into your machine via USB. You will be then asked to authorize communication with the computer you have connected to. It will also show computers RSA key fingerprint.
Accept it and you are good to go!