How do you become friends with animals on Animal Crossing Wild World DS

You talk to them every once in a while. You complete their tasks and they give you gifts. You will have to talk to them every time you go on Animal Crossing because if you don't they will leave your town. Make sure not to talk to one character like twenty times because he/she will call you a stalker.
If you are successful, your animal friends will give you his/her photo.