Wear a helmet so they won't give you static about their wearing a helmet. Tiaras are cute for skaters who are "moving," but helmets keep their brains safe at the SS/Basic 1&2 levels. Toddlers are top-heavy, so they usually whack their heads when they fall.
Practice sitting down and getting up OFF-ICE first. Take five or even ten minutes and also march around, check for tight skates, swap hockey for figure or . I also teach how to safely get on the ice side-saddle without stepping on the threshold. Makes a huge difference in getting the class running on the ice.
Keep kids 3' from the walls, so they won't lean and fall, whacking their heads. Just as important, they won't have a parent in their face on the other side of the wall. Some parents wave, talk to the kids and distract them from the class, or worse, set off a "I want my mommy" tantrum.
Play a round of "Duck, Duck, Goose" to practice sitting down and getting up.