One would be hard pressed to find someone with better credentials for teaching science fiction than 10 gazillion time Hugo and Nebula award winner Orson Scott Card (most well known for Ender's Game).
I recently read his book How to Write Science Fiction & Fantasy Although some portions were too philosophical for me to find immediately helpful, he gives insightful tips on world building and plotting, and the excellent chapter on exposition is itself worth the price of the book. Here are three tips from the book that I found particularly useful.
1. The idea net - The idea of making up a whole universe, with peoples, cultures, landscapes, and histories can often seem overwhelming. That's why I liked Card's approach, which is to start with one or two ideas and expand on them by asking questions and following them to their logical conclusion.
He uses Ender's Game as an example. First he started with the idea of kids playing battle games, and then asked questions -- Who are they fighting? What is the goal of their training?
Likewise, if you are making up an alien species, first start with a few characteristics (another of Card's examples -- they communicate by transmitting memories directly via DNA) and then ask questions. For example, how do these characteristics influence their society and government? Why would such characteristics evolve?
Card sometimes runs workshops where the class uses this process -- asking questions, improvising answers, and repeating. The results are almost always workable into a story.
2. Exposition in Science Fiction and Fantasy - A unique challenge of speculative fiction is the need to acquaint the reader with an entire world and all its relevant quirks and details. How do you do that without clunky descriptive paragraphs or artificial explanatory dialogue?
Card addresses this issue by analyzing an example of skillful exposition: the opening of Octavia Butler's Wild Seed. A summary is no substitute for his actual analysis, but the basic point is that much can be shown through subtle details. For example, referring to a village as a "comfortable mudwalled place" tells the reader not only about the setting (primitive), but also that the point of view (POV) character feels comfortable in rustic surroundings.
It is not necessary to break POV and give characters artificial thoughts in order to fill the reader in. In fact, good use of POV will create a deeper and fuller sense of the setting. Details like whether or not the character regards items and events as unusual or commonplace, happy or sad, fair or unfair, will be picked up by your readers and incorporated into their impression of the world.
3. Creating a wise reader - How do you get feedback from friends and family beyond the polite but not very useful "Yeah, I liked it"? Card suggests that the secret isn't to get people to tell you how to fix your writing (Add more description? Bad characterization? Faulty plotting?), but to train your "wise readers" to report their own personal experience while reading. If they can tell you when they felt bored or excited, when they stopped reading, and when they felt something was missing, then you can go back and figure out how to fix things.
Overall verdict: There's lots of good stuff in this book. I'd highly recommend reading it at least once, and I myself will probably read it multiple times.