Select a container sufficient in size and that complements your home decor. Old garden urns are ideal for large, impressive arrangements. If you use a garden urn, find a plastic insert that will fit inside the urn without showing to prevent leaks.
Place the plastic insert inside the urn and fill it with floral foam. Cover the insert with chicken wire so that the chicken wire forms a dome that is secured just under the inside lip of the urn. Don't worry about making the chicken wire appear neat. Trim any excess chicken wire with wire cutters.
Soak decorator moss in warm water to make it more pliable. Cover the chicken wire with the damp moss.
Cut the twigs at an angle using sharp garden snips. For fresh twigs, this removes the dried ends and helps them absorb water. If you're using dried materials, the angled cuts help the twigs slide into the floral foam without breaking.
Insert twigs of various heights and shapes through the moss and wire so they stick into the floral foam beneath. Occasionally step back from your arrangement to make sure the overall design is pleasing.
Add any complementary pieces to your twig arrangement, such as tall, wispy grasses for contrast or live plants. Add water to the plastic insert if you use live plants.