Seeing the similarities rather than the differences. Most, if not all human beings, have the Five Hindrances going through their head -- they're not any different to us. They have a body just like us. They are subject to the conditions included within Five Daily Recollections that the Buddha encouraged us to do: they are subject to disease, aging and death just like us. They are subject to the Law of Kamma, born of their Kamma, heir to their Kamma, related to their Kamma, abide supported by their Kamma, whatever Kamma they shall do, of that they will be the heir.
Most people who have prejudices are too focused on the differences rather than the similarities. They are focusing on the different color of the skin or the different religions or the different this, or the different that; rather than seeing the similarities, and being able to understand suffering and the true cause of it, seeing that all of us have Dukkha. As we develop this view of others, seeing the similarities rather than the differences, we come to more of a compassionate view of others, and understand that we are part of one big family.
This does not mean that we don't discriminate. Having Compassion for somebody else or other people doesn't necessarily mean that we associate with them. This is balancing our Compassion with Wisdom, because we need to protect ourselves and understand the suitable conditions for our growth as well as the suitable conditions for our peace and well-being. This is something that often people do not understand and they believe that if they have Compassion for someone, then they have to associate with them and allow them to do whatever they want to do to us. This is not the case. Compassion has many faces and needs to be supported with right understanding of the Law of Cause and Effect. In that way, we can learn how to protect and prevent ourselves from putting ourselves in conditions that are harmful. However, this doesn't prevent us having Compassion for whomever we do not wish to associate with.
There are many people in the world that I don't wish to associate with but that doesn't prevent me from having Compassion for them. In fact, if they are harming themselves and harming others, it actually makes me bring up more Compassion for them, because they don't know the true cause of suffering and don't know how to end it within themselves.