I found when I blogged my Legacy Challenge family, I had far more fun playing the legacy. They can get 'dry' since you have to go from the Founder until the tenth generation heir is born. I only had one time when I was stuck on what to write about. I tend to play and let what happens in the game be my guide to write, rather than have a plotline to follow. When nothing material happened, I was at a loss. Then I decided to make up a situation and went from there. Most of the time my Sims created their own drama and I just provided the motivation behind the actions.
If you enjoy writing as much as I do, (it's like breathing to me), then go for it and have fun!
http://galacticgals.blogspot.com/2014/09/chapter-one-eriks-choice.html