Write it down.  Put it on paper.  Make it concrete.  Now go a step further and do something creative around the dream.  Draw a picture of it.  Write a story based on it.  Write a poem with it.  Dance it.  Sing it.  Find a small object or totem that represents the dream and carry it around with you for awhile.  Share it with a trusted friend – not casually as in “Wait till you hear this crazy dream I had!”  Share it quietly, reverently, prayerfully as if you were sharing a very precious part of your soul – because you are.  Love your dream.  Love them all.  Even the terrible ones.  They are the best ones, really.