A critical aspect of motion for material design is to retain the feeling of physicality without sacrificing elegance, simplicity, beauty, and the magic of a seamless user experience. Here are some guidelines to help translate these concepts into animations.
When an object enters the frame, ensure it's moving at its peak velocity. This behavior emulates natural movement: a person entering the frame of vision does not begin walking at the edge of the frame but well before it. Similarly, when an object exits the frame, have it maintain its velocity, rather than slowing down as it exits the frame. Easing in when entering and slowing down when exiting draw the user's attention to that motion, which, in most cases, isn't the effect you want.
Not all objects move the same way. Lighter/smaller objects may accelerate or decelerate faster, because they have less mass and require less force to do so. Larger/heavier objects may need more time to reach peak speed and come to rest. Think about how this applies to the various UI elements in your app and consider how their motion should be represented.