Some other stencils I've done over the past few days below.
For all of these I erased the background by filling it with a contrasting color and then erasing the contrasting color with Mehdi's "Eraser Classic" filter because I hadn't figured out to outline it on another layer. But, for something like the branches one, that is definitely going to be the easier method of erasing the background anyway.
I also used the optional 2nd filter on all of these. It was just with this last one I was doing as an example that the 2nd filter darkened everything too much.