Some of my best ideas for my stories are from my dream and as such I need to remember my dream when I wake up.
I had read this somewhere when I was 15 and this is what I do:
When you are on bed, close your eyes and try to focus your attention as if you are trying to see something that is right in between your eyebrows and then tell yourself that I will remember my dream and you can even dictate what you want to dream. You also say that I will remember what I dreamt when I wake.

Quite often this works for me:)