The fact that you want this tells me you are already a good person. As for how to become a more compassionate, sympathetic person, I think just being aware of your thoughts as they come in. Example...you see someone and you have a negative judgement pop into your head about them. Grab that thought and ask yourself why you feel that way. Is there something in your past that causes you to jump to that negative conclusion? Then challenge that thought...see the person a different way...think of what may have gone on in that person's life to bring them up to the point that you have met them. We don't know what causes people to be how and who they are. If you do this for a time, you will notice a shift in how you perceive people.