Just cut stars in increasing sizes and string on thread.
You could also use Glitter Fabric.
Use anything to decorate - sequins, beads, buttons or tinsel stems.
You could use glitter fabric or snowflake felt.
You could use a cookie cutter for the shape.
Use glue to stick pompoms, Bells etc. to Polystyrene Ring.
You could use beads or bells for the ends of the branches