We actually have four or five dreams every night, so the problem is usually remembering them all in the morning instead of making the dream itself longer. Since you've experienced it once, maybe you can just try to copy your state of mind when you experienced it because you've already found what "works" for you personally. What works for me personally is centering to sleep, but you can also check out lucid dreaming techniques on Wikipedia. As for sharing a dream experience, that may be more an astral projection, but here's a source on dreamwalking.
I agree with the above, I heard that simply writing something down improves your chances of remembering it. Try keeping illustrations in that journal, too.
Get a dream diary, keep it under your pillow and the second you wake up don't move, and focus on recollecting as much of your dreams as possible. After that, even if it's just the tiniest detail of the dream, write it down.
After a week or two of that you should have longer/more frequent lucid dreams. While in reality, ask yourself the question, "am i dreaming?" I know it sounds stupid, but it works, that way when you're dreaming you get used to asking yourself that, triggering the conscioussness within.
If you feel your dream is coming to an end, start spinning around in circles, it makes it last longer. I also found a strangely affective method of screaming, "lucidity now!" as if making your mind grant you lucidity. Eventually you will get better, but always search the web when you need more info. etc. on various sites, gather knowledge and collect it!
most people have mobile phones able to record their voice and set as an alarm call.
Record yourself with a command that is short and to the point:
Suggest 'is this a dream?' 'am i dreaming?
set alarm to play this message at say 2am and 5am
combine this with other training exercises for lucid dreaming.
Post me if you are interested in these ideas as this i have been developing more techniques
