You don't need wires, oases or willow - first find as much greenery as you can.
I usually start with lengths of ivy (variegated is good),, formed into a circle and twisted round and round on itself until it's reasonably firm.
Don't make it too big as it will sag when you hang it.
And you can secure it with garden string or wire to keep the shape.
Then snip of some bits of Christmas tree or conifer, shove these in round the edges (again, use string or bits of wire to secure), you can also go around the inside if you like.
Add in bits of holly, any other greenery you fancy, maybe fake berries from Hobbycraft.
Then glitz it up as you wish - I like a big bow at the top and a fake bird, but have also done one with a blue bow and three blue/silver baubles hanging at different lengths.
from the top.
Cinnamon sticks and dried oranges an option, obviously, as are pine cones, fake apples and pears - whatever.