I rarely have good dreams, only nightmares. I never remember them either, well, only four of them to date.
I had one last week.

My sister was pushing me backwards over a cliff. She was laughing while she pushed me. It was in a location like the Grand Canyon. When I was falling there was nothing below me. I did not hit bottom, nor did I stop falling until I woke up.
I was told this may actually be a good sign. Can anyone help me with this? I'm kind of freaked.

Thank you.

Maybe your sister wants you to understand her or listen to her. Maybe she just wants you to be her brother and have some fun together. Falling down the cliff might represent her wanting you to take control and lead your life. She's telling you that you need to let-loose and go on an adventure.