Hey Ben. I am no Pro, but have some experience. First off, you don't need a second camera. It can be helpful sometimes, but really it is nothing you can't do with one.
Also, I highly recommend a handheld stabilizer. It will make a world of difference and liven up your shots a bit. I personally like the look when the camera is moving... just best when smooth. I shot the below below with a Canon 6D on a GlideCam with a RODE Mic on my camera. We had a second camera, which was only used for up close shots, the rest was me. We used the audio from the RODE mic as well.
Hope this helps.
