The cardinal rule: do not treat the crew as if they are below you. These people have spent ample time in the "biz" and likely know more about your job than you do.
At the same time, be sure to establish this is your crew. Do not be mean or nasty, but make sure everyone is on the same page.
Most of the time, this can be accomplished by a simple meeting or dinner in which you explain the respect you have for them, but need them to be supportive, not anarchaic.
Engage them in collaborative discussions. Even if you never plan on using their ideas, letting them express thoughts and opinions shows that you care.
On the whole, avoid any form of authoritarianism. Regardless of the type of crew, filmmaking is a collaborative process. You are working with the same people for 14 hours a day, for a few months.
Show your appreciation. Buy extra dinner, arrange a party, whatever, to show that you are thankful for all of their hard work.
Be mature. This is a professional setting and nothing will anger an experienced crew more than someone without experience acting like a child.