The way to learn to trust your intuition is to trust your intuition.  It sounds simplistic, but through experience I am coming to believe this truly is the way that works for me, and maybe it will for you too.  When I really listen to my inner voice (or gut, or the angel on my shoulder, or whatever you call it) then that voice seems to get stronger.  When I second guess myself, and start to doubt what it is I am hearing, the voice gets weaker.  Can it really be that simple?  Or maybe the question really is: why do I think it has to be so hard?