Recently I also started a new one using nails as connectors and stairways between the different parts of the structure. It seems that my twig structures, like my maps, always come back to the idea of making a visual and practical path among the elements. I'm always trying to make sure that other viewers will see the same connections that I do, but the differences are interesting too.
When I make freestanding structures like this, I use clothespins to hold up the main branches in the right arrangement until I've put all the connectors in place. At this point, the structure can actually stand on its own, but I've left the clothespins (as you can see in the first photo) because the twigs are balanced in an only barely stable way.
I also have one more that uses toothpicks and spent matches as complex connectors, but I don't have any good photos of it at all for some reason. I will post more once I get them all finished and up on the walls!