Introduction:If your kids are like mine, they will be heavily into Superman, Spiderman, Wonder Woman, etc. Since they are exposed to this anyway, why not properly introduce them in the first place? Here are some tips...
Let them know that superheroes are always moral. They do not kill and always strive to do the right thing. Do not confuse with superheros who are morally suspect (e.g., Watchmen). Children need their heros to be role models, period.
Make sure your children admire the mental/moral qualities of each superhero in addition to any physical ones. They need to feel that for them to be more like their heros, they need to develop their qualities of honesty, caring, justice, etc. more than any physical attributes.
Make sure your children understand that no matter how much they like their superheroes, they need to understand that they are not real. If you are religious, they also need to understand that Jesus, God, etc. are the true superheroes.
Let your kids know that no matter what powers superheroes have, the strongest ones are love, compassion, etc. Let them know that it is much tougher to show these qualities than having the strenght to smash through a wall. As such, they may come to realize that parents are the greates superheroes.
Finally, it's good for them to admire the physcial health of each hero. There are no overweight heros. So, encourage your kids to exercise and be active.
select one here...