U = Using Your Characters. Okay, at the other end of the alphabet, it starts to become more tricky to work out a suitable caption! I would say Using Your Characters is to be avoided. Each and every one of your "people" should have a definite reason for being in your story and if it isn't strong enough, cut them out. Sometimes combining two weak characters into one can create a stronger person, who you can justify keeping in the story. So your characters then aren't there to be used. They are there to drive your story and if they're not doing that, out they go!
V = Vital Information. Yes, I could have gone for verbs (!) but I don't really want to write a grammatical post. Vital Information is anything your readers need to know to make sense of your story but that doesn't mean you should give it to them "wholesale". Drip feed information otherwise blocks of text will just switch your readers off. Don't necessarily spell everything out. Give your readers enough information so they can work things out. It gets them more involved in your story and that can only be a good thing.
And now for a few days to work out what I'm going to write about for X and Z when I get to them!