First, check to see if your local waste management recycles Christmas trees into wood chips (that's a great option if you have it!). If not, get an axe and get to work – turn your tree into firewood and use the needles for much. Live near a lake or pond? Wash your tree with the hose (get any glitter, plastic, and hooks of of it) and toss the tree into the lake. The tree is a natural incubator for algae and great habitat for fish.
Got stuff you don't need? Instead of throwing it all in a box and sending to the thrift store, think about who could use it and donate to specialized organizations that will get it to people in need. Transition houses, homeless shelters, animal shelters, disaster relief organizations, children's programs, family assistance leagues... what you donate now will be used throughout the year.
Happy 2020 - let's make it the most sustainable year yet!