You do have a Dream Journal, right? It helps to improve your recall dramatically. You might not have started one because you don't think your recall is good enough, but writing down any little fragment will help improve recall. Even if all you get is those short, hazy, 5 second recollections, write them down. I have an entry in my DJ that just says "Floating musical notes."

If you do have one, I suggest subliminal recall, and Ryuifinity stated...

Also, as soon as you wake up, DON'T MOVE. If you do move, before you think about it, get back into the position you woke up in. Then just lay there for a minute or two and try to remember all the details you can. You will be able to remember dreams much easier this way.