This can't be reiterated enough. If your crews don't trust you, the changes you will attempt to make will often get overlooked or even worse completely ignored. Be patient, trust takes time and effort to build and there are two essential steps to building that trust.
The first step is having open discussion about your expectations of your crews and what their expectations are of you. The second step is being consistent in everything you do. These two things, if done well will provide a strong base in which to build and maintain trust among those around you. In contrast, if you do not discuss expectations and provide consistent leadership trust will never develop and gaining forward progress will be frustrating.
Once trust is starting to form, make subtle changes by addressing the "low hanging fruit". This is the easy stuff that will effect morale positively. You can then start to work together on the more difficult items and monitor progress. With that said, do not use the perceived morale of your crews as a gauge on how well you are doing. Morale is fickle and is ultimately driven by the attitude choices of the individuals. Your success will be evident by the conversations that continue, when you enter the room. Allow for honest feedback and then listen to them, they have great ideas.
The true test of your success as a leader is not shown by how your crews are when your there with them, but more about how your crews carry themselves when your not around.