Just a very quick idea that, I think, turned out really nicely:
Combine fir or any (green) branches, painted twigs, Christmas ball ornaments, stars, angel hair, ribbons, bows, fabric remnants, Christmas figurines, tree bark, moss, fir cones, …. in a flower pot until you like the arrangement!
You could put floral foam in the pot for better stability. Me and my mom tucked everything in soil which worked just fine.