Tether on USB
It is difficult to setup a tether connection to usb.
This is what I do to get it up and running but I often have to restart my phone to get it working:
1. switch ON tethering over usb (on the phone) and check that a connection is made (without Orbot)
2. Switch OFF tethering in the Orbot settings and start a Tor connection in Orbot
3. Check that the Tor connection is active on my phone
4. Switch OFF the Tor connection in Orbot
5. Switch ON the tether option in the Orbot settings
6. Make a new connection in Orbot
I am not sure but it seems that the problem is related to a delay in the availability of the root rights that are given to Orbot. When I directly try to start Orbot with the tethering option ON in the settings it doesn't work.
I use a Galaxy S4 that is rooted running MIUI