You are asking some challenging and profound questions. I like it!
I can delve into the subject without first questioning your assumption that there is a higher power, because it is true in my experience.
And the timing of your question fits neatly with a hub just published, "How to Regain Connection with Your Higher Self."
The subject easily filled a hub, and answering your question would fill another. I will follow your writings with interest.
Oddly, focusing too much on discussing the subject can diminish our experience, as it becomes intellectual and the ego is satisfied without actually living it!
We will serve higher power when we aren't thinking about it, when it is a natural act from a pure heart. We can choose our values and wantings consciously, practice the art of letting go, accept the happening of life, internalize our authority rather than give it away, and clear the obstructions within for higher power to flow.