Most children enjoy dressing up and pretending to be someone/something else. This is a common part of play among preschool and early elementary kids. Halloween is a great opportunity for kids to use their imagination.
In general, costumes for very young children should be of familiar characters, people or objects and not cover or alter the face. By second grade, most kids understand the difference between reality and fantasy. Watching your cousin put on a scary mask can still be frightening for some of 6 year olds. If Ursela and the Wicked Witch of the West are characters your child dislikes, be proactive in helping your child avoid interactions with big kids that might enjoy werewolves and mummies.
Thirty years ago, almost all Halloween costumes were home made. Consider reviving the tradition. A paper grocery bag can be cut into a vest and decorated as a police officer, native american, cowboy, etc. Paper plates can be cut and safety pinned to the back of a shirt as wings for a fairy, angel, insect or princess. Parents can help add glitter to the edges. Paper or fabric letters can be pinned to a shirt to create an athletic jersey. Spots can be added for a cow or dog. Stripes can be added for a tiger or bumble bee. The school glue that advertises it is washable is an easy way to attach ribbon for stripes and they conveniently come off in the wash.
Trick-or-treating is an old tradition. (The History Channel has a good explanation of its origins.) Past generations of children took candy from strangers on Halloween. You have probably already tried to teach your child not to accept candy from strangers. Halloween is a good opportunity to see how well your child understands.
If you ask four year olds what a stranger is, many will not be able to answer. Those who do will mostly fall into two categories: a person you don’t know and a bad person. When I ask kids I have never met before if I am a stranger, many say no. Some justify it because they know my name. Others justify it because I have been talking with them a few minutes. Some assume that if I know their parents then I am not a stranger.
Candy and rides are often mentioned when teaching children about stranger safety. There are lots of other enticements that are used to lure children. If your child is old enough to understand, give a quiz asking if it is ok to take specific things (money, candy, stickers, toys) from people they have never met, people their parents know, etc. Just talking about it before Halloween can give you a great opportunity to reinforce the lesson when you Trick-or-Treat. If you are going house to house, explain how you do or don’t know specific neighbors and qualify them a strangers or not. If you are going to a trick-or-trunk event in a parking lot, explain how you know that the adults giving out treats are safe. If you go from store to store in a mall or booth to booth at a fair, you can ask about who strangers are and what behavior is safe.