When you recall a dream scene, recall what happened before that, and before that - relieve the dream in reverse. Do that for several minutes. If all you remember is a mood or feeling, record it in your journal. Even if you can't recall anything in bed, events or scenes of the day may remind you of something you dreamed the night before. Be ready to notice this when it happens, and record whatever you remember.
Some people sleep very deeply.
If you do, set an alarm clock to awaken you at a time when you are likely to be dreaming. REM periods occur in approximately 90 minute intervals You might want to set your alarm in multiples of 90 minutes after you go to sleep. The later REM cycles are usually the most active. When you awake, remain still and let your first thought be of you just dreamt before you begin to write. Before you go to sleep read your dream journal.