There is nothing family members can do that is wrong but there is is a lot they can do that is unproductive.
Isolation, shame, fear, anger and trying to control the wrong things are the biggest hurdles the family must overcome. Family members want to know; How can we help? The first step in helping is to find support reduce the isolation related to the addiction is your family.
It is important to understand that what ever you do to "help" must, first, be motivated by the need to take care of yourself, both, physically and emotionally. Family members tend to put their emotional well being into the hands of an addicted person who has no control over their own well being. They say to themselves, "I can never be happy unless my loved one stops using drugs." By doing this family members make themselves into emotional hostages to their loved one's addiction. When this happens the family winds up feeling the pain and anxiety that the addicted person should be feeling and needs to feel to have a chance of making a decision to get help.
When family members buffer the addict from the consequences of their addiction they rob the addict of an opportunity to struggle with a crisis that may give them the motivation to seek help. Why do family members do this? Because they think they are "suppose" to rescue their loved one and because they are also trying to soothe their own anxiety. If family members reach out and allow themselves to get support they can learn to not do for the addicted person what they should be doing for themselves.