Yesterday I started playing around with a second novella to follow Tequila Sunrise, my 23K word story about 2 people who meet on a cruise ship and have to go back to very different worlds after 4 days at sea. Early on in that one, I thought it might be fun to write a second story using some of the minor characters. It's the first time I've ever done that, though readers often ask if/when I'll write a sequel to one of my novels.
It was interesting, to begin chapter 1 when I already knew a lot about the characters and the setting and the situation. Actually, it gave me some freedom to just jump into the first scene completely in the middle of action that was happening in the first book. Eliminated all that introductory stuff (the way you're supposed to, ideally), even though I know I do have to fill in a few blanks if people haven't read the first one.
Still, it was fun...in the opening pages, anyway. I know series/trilogies are very popular with readers, so it will be interesting to see where this goes. I'll keep you posted!