If you are learning ASL try to pay special attention to how much facial expression deaf people use. At first you might think they are exaggerating, but they are not. So, when you sign try to use as much facial expression as possible. It is equivalent to our intonation. If you don't use your facial expression it is like having a conversation with a person who is completely monotone.
If you ask most deaf people if you are using enough facial expression they will tell you that you could use more. So, my challenge for all of you hearing signers out there is for the next time that you are signing with a deaf person, try to use so much facial expression so that they have to tell you that it is enough or too much. I bet you have a hard time getting there. Now remember they are the best example for you. So try to follow their lead and do what they do.
Remember to always have fun while learning a new language. Before you know it you'll be signing rather fluently.