People will advise you to write all sorts of sentences. Snappy sentences, lyrical sentences, Hemingway-esque short sentences, long Faulknerian sentences. But there's really only one kind of sentence that actually works: a sentence that carries the reader forward from the previous sentence. This is harder than it sounds.
I don't care what kind of fiction you're writing. Introspective or action-packed, sprawling or tightly focused, character-driven or idea-driven — it doesn't matter. You can write any kind of story you want, and this still applies. Each of your sentences has to build on the previous one, propelling the reader forward.
Usually, I'm a big fan of saying there are no rules in fiction-writing, just suggestions and lists of things that are hard to pull off. But I've been thinking about this one a lot lately, and it feels pretty iron-clad: Your sentences should build on each other.
Part of the joy of reading, especially fiction, is the feeling of being swept forward by narrative, and following the chain of statements from A to B to C. We read to "find out what happens next," but also just to follow the thread.