I have approached storytelling with TS4 in two different ways.
First I've tried my hand at making Machinima movies. With that I treat my Sims as actors so all the interactions are geared towards creating a scene I can video capture. You can make decent soap operas with that but it's best to script them as much as possible first so that each scene is building to a point of action or drama.
The second method is the text with pictures style. In this I play the game pretty much as standard but I'm looking for cues from the Sims so I can write it up as a story later on. Recently, I've had a potential date fall at the last hurdle and my main sim getting "friendzoned". In a standard game of Sims I might ignore that one time bad experience and push on another day until the date finally agrees to go out with the sim because you can game the interactions that way to get what you want, but in the storytelling mode I'll run with the rejection and frame future chapters around that incident. You need to pay attention to the little subtleties with interactions and spot where the story possibilities are.