Most of Dreams occur when people are thinking alot, I mean a lot. Dreams are what's happening in person's life. Sometimes dreams are telling us future and trying to prepare us for change which will occur soon from seen that dream.
Depending on a dream is up to us whether to remember it or not because by concentration on dream one could attract the events from the dream into life.
Spiritual people see visions most of the time. The visions are not like regular dreams they are like real events and the dreamer knows if he/she saw a dream or had a vision.
I do follow my dreams but the way I should. When person following his/her dreams he/she will write them down in a special note book. By writing down dreams one could keep track better and come back to the dream any time to connect the chain of events with dreams and life events.