Ornament numbering (1-7) roughly correlates with difficulty of printing. Regardless, getting the first layer stuck to the build platform, and printing with a thick brim, are essential. Some of the ornaments have very aggressive overhangs, and having your cooling and print temperature dialed in is essential.
"The parts are represented as a solid (ie - filled) because I was getting the best results by letting the slicer create the shell surface. You can print them "without a bottom" in Cura and get a print with a hole in it for hanging, though I found it easier+stronger_faster to print them with uniform 2mm walls all-around, 0% infill, and drill out the hole for hanging afterwards.
Printed slow and cold: 0.1mm, between 25-50mm/s (depending on the part complexity) and around 205° using Printbl White PLA. Each print took 5-10 hours....general strategy was to set up a print before bed, babysit the first 5 minutes of the print to make sure it stuck crazy well to the build platform.... and then wake up to a finished ornament in the morning."
Ornament toppers: http://www.thingiverse.com/thing:189367