1. Get as involved as you can in the deaf world and learn about deaf culture.
2. If you get involved in a club or activities, do not take over. Let the deaf people be leaders since it is their club or activity. Many deaf people are resistant to hearing people who tries to take over because of their past experiences.
3. Be friendly and open to learn anything.
4. Be very accepting because our culture is way different from yours. Do not try to change anything.
Those are what I believe makes an interpreter a good interpreter. Knowledge and accepting of deaf culture. When you socialize with deaf people, you will learn to adapt to various signs. Each deaf person sign is different, just like hearing people voices are. All interpreters need to know this because so many times I have run into interpreters who cannot understand many people signs because they only learned sign in classes with one deaf teacher.
There is an interpreter I have known since I was a little girl. SHe and my mom took ASL classes together and those are the info she gave me a while ago. And she is just a wonderful interpreter. She also has told me when she is in a meeting with a deaf person and a hearing person and something that was said was not clear, she does not just interpret it. She stops the person talking and ask them to make it clear just so she can make it clearer for the other person. Changing ASL into spoken english and vice versa is not the easiest thing in the world so it is very important for you to understand everything in order for everyone else to understand.
I hope I have said it all..
Good luck! 
