The following is a five step visualization for developing compassion taken from His Holiness The Fourteenth Dalai Lama's book
How to practice the Way to a Meaningful Life

Morality of Concern for Others

1. Remain calm and reasonable

2. In front of you to the right, imagine another version of yourself, egotistical and self-centered.

3. In front of you to the left, imagine a group of poor people, suffering beings who are unrelated to you, neither friend or enemy.

4. Observe these two sides from your calm vantage point.
Now think "Both want happiness. Both want to get rid of suffering. Both have the right to accomplish these goals."

5. Consider this. Just as usually we are willing to make temporary sacrifices for a greater long term good, so the benefit of the larger number of suffering beings to your left is much more important than this single egotistical person on your right. Notice your mind naturally turning to the side of the greater number of people.

Action

Consider putting a bag of snacks (energy bars, fruit, chips) in your car or in your backpack. When you see someone standing on a freeway on-ramp asking for help, or downtown standing on a corner, just reach into your bag give them a snack and some words of encouragement. This is really easy, they will appreciate you help and you will feel good about dong it. It will increase your capacity for compassion which is the basis of world peace
Namasté!