How can I heighten my clairaudient ability?

First off I'm not on any drugs so no smart *** answers please. My godmother is a professional spiritual psychic and has told me I have a little esp going on and other manifestation gifts I just am not in the positive mind frame to master them right now. The gift is from God and when I am in a negative state I hear negative entities...For the past 4 or 5 years about a few times a week, I've been hearing conversations of spirits or people that moved on when I'm either relaxed, alone, or about to fall asleep. Sometimes I get so scared that I freeze up and block out the voices. I hear usually multiple voices speaking either to each other or whispers to me. I don't hear it threw my ears more like i hear them talking to me threw the temples of my head. Does anyone have any advice for me on how I can master my gifts and use them when I want and when I want to shut them off.