There are a million ways to improve ER, but one way is to teach leaders to be transparent. Trusting employees goes a long way. Leaders that share information have higher employee engagement. Communicating clarifies decisions to the employees. It makes things like the mission and vision clearer, and employees suddenly understand that the goal is something worth contributing to.
Otherwise, start with a survey or focus group to understand the biggest pain points in your workforce. Start work on those, and create a plan for the rest.