A time ago, i was able to avoid nightmares.
Whenever i was about to get one, i would see my room (allready in my dream of course) fully lit, like there was a light on.
Then i was able to think of other (good) stuff and i would wake up.
If i didn't or if i didn't do it well, i was going to have a nightmare.
It was friggin' awesome, but the sad thing is, after a while, i didn't remembered my dreams at all (,like if i never got any dreams).
Though i am still waiting on that one dream in which i have full control over it. >=D
I would love that and some say it is possible, but i am too lazy to write down all of my dreams when i wake up. :P
Full control over my dreams would be like, playing games with your own mind as console. =O