This is a very versatile rig with a lot of possibilities... but you have to remember to apply the same principles of animation to every controller on the rig that you would to a hand drawn animation. In the first 80 frames, you should have the character lean into the gesture asking for a refill and maybe hold it for 12-16 frames before going to the next pose. Also, rotate the chest as hes leaning to one side to give the upper body more weight. The hips should shift weight a little bit when he sits up also. Remember ease in and out. You're moving in straight lines. Trace out the arcs of movement in the hand (you can use a dry erase marker on the monitor to track your arcs). You're getting it though. Keep animating
Also, remember that the whole body moves, not just one part. Even if it is subtle, you will need to animate just about the entire torso. Puppets in maya look too stiff if you apply too many limited animation short cuts to them. That is the challenge of 3d.