I take a jpeg like this and import it into Aspire (should work the same in VCarve), then use the trace bitmap option.
The higher resolution the picture, the better. When I use trace bitmap, I keep tweaking the settings until I get it just the way I want it. I then use v-carve toolpath (I think I used a 45 degree v-bit) to cut the design into the wood. Here's how it turned out on a piece of oak: