One of the strategies I've been trying with my small reading groups is "somebody wanted but so". I create a chart with those categories and we collaboratively fill in the boxes. It's a very guided approach to summarizing and my students are having a lot of fun with it.
Example: (the Lost Hero)
Piper (somebody) wanted to rescue her dad and stay loyal to her friends but she was worried how she could do both so she told Jason and Leo about her problem and they decided to help her.
I also found this on pinterest:
I like that it adds the "then" category for students to explain how the problem was solved. This teacher suggests using post-its and I think that would be a great way to introduce the concept, but I wouldn't necessarily use it every time.