Make cookies one day in advance. Prepare cookie dough and roll out following recipe directions. Use tree cutter from set to cut shape. Bake and cool cookies.
Ice tree cookies. Prepare Color Flow icing. Tint portions red, green and light green. Reserve some white. Use tip 2 and full-strength green icing to outline cookies. Use thinned green icing in cut disposable decorating bags to fill in. Let dry 24 hours.
Decorate sparkly white tree cookies. Use tip 2 and full-strength white icing to pipe wavy lines. Sprinkle with white sugar. Let dry 1 hour.
Decorate sparkly green tree cookies. Use brush to brush piping gel on cookie. Sprinkle with green sugar. Let dry 1 hour.
Decorate wavy green tree cookies. Use tip 2 and full-strength light green icing to pipe loose zigzag. Let dry 1 hour.
Decorate red swag tree cookies. Use tip 1 and full-strength red icing to pipe red swags. Use tip 1 and full-strength white icing to pipe dots on point of swags and on tree top. Use finger dipped in cornstarch to pat smooth. Let dry 1 hour.