I think for a beginner, or anyone, a straight ruler with the markings on it, a gentle arc and a 1/4" gauge are essential.
You can get all of those from Westalee and other manufacturers sell the rulers, but I'm not sure about the gauge.
The gauge is to use to assure yourself that the far end of the ruler is in the right spot so you end up where you want to be. I had never seen one and now that I have one I wouldn't trade it.
I've also heard that Quilter's Apothecary sells rulers with a handle and have videos for most of their rulers, so that might be helpful.
Watson