Wrap the wreath form with yarn. Get the yarn as close together as possible so the wreath form does not show through. Alternately, you could use a white wreath form to make this a bit easier.
Trim the end of your yarn and secure it in place with hot glue once the wreath is completely covered.
Start adding on pom poms with hot glue. You will need several pom poms to get the same look on your wreath. You can definitely make these from yarn if you would like instead of buying the ones that are pre-made.
Once you have your pom poms in place, add in bottle brush trees of all sizes with hot glue. You can add as many or as few as you would like. Then hang this one on your front door.