Simply install this program on your Android tablet then select "Configure" to pair with your phone. If you haven't installed the PdaNet+ app on your phone please first do so from Play Store (or http://pdanet.co/android if Carrier delists tether apps) , then open it and check "Bluetooth mode".
*Limitation*: Since a lot of network apps specifically look for WiFi connection on start up and do not realize (or consider the case where) Internet is available through Bluetooth. They will fail to load. One way around this is to connect your tablet to a random WiFi hotspot at the same time, even one that doesn't give you Internet access. For example if you have a Windows computer nearby you can turn it into WiFi hotspot using the "hostednetwork" feature and connect the tablet to it. Or consider the following solution.
The Browser app on Android is not affected by the above issue. So if you have an app that fails to detect Internet, try to see if there is a web version of that app. For example instead of using the YouTube app you can go to http://youtube.com using the browser.
The above limitation is not ideal. However unless you can turn your phone into WiFi hotspot, this is the ONLY way to tether an Android tablet to and Android phone since USB connection does not work.