Dear Recently Awakened,
This is a great question! Just for the simple face that you are asking how to promote tolerance in children means that you are conscious of teaching children these values.
In this day and age, we all must learn tolerance and acceptance of others. With so many diverse cultures and societies, it's impossible to learn and grow as a person if we reject any ideal that is different from our own. It doesn't mean we have to adopt other values or beliefs, but to have respect that there ARE values and beliefs different from our own. I would suggest that as issues come up with a child, first educate yourself on the subject and then educate the child. Speak to the child from their world, as they may see it.
For example, a teen was highly agitated about another teen's "staring". She reported that the other girl stared at her constantly, which made her feel uncomfortable and defensive. The girl who was "staring", was from another country, so I researched and found that strong eye contact was part of their culture. Looking intently at the face was a form of respect. When this was explained to the girl who was being stared at, she gained a different perspective. This made her feel differently about the other girl's strong and direct eye contact.
It's important to understand the situation and relay information in a non-judgmental way. Such as the story about the teenage girls, neither perspective was wrong, their cultures simply differed in terms of eye contact.
I hope this helped!