Well, I find its easiest to remember when I wake up without an alarm. I just keep my eyes closed and do my best to remember every single possible detail of the dream. I repeat them over and over again in my head until I have it memorized perfectly. Then I open my eyes and write it down. The second you open your eyes, your brain starts to forget your dreams. So the trick is to keep your eyes closed upon waking and think things through before opening them. You could also try dictating a dream journal, if you have a suitable small recording device to keep nearby. Good luck!