If you want your space opera to be awesome, you must practice the Rules of Space Opera (not to be confused with The Rules). Want to get in on the secret that has made everything from Star Trek to Battlestar Galactica into the objects of such longstanding adoration? Read and learn, cadet.
1. Have a giant object in space.
I don't care what it's for - hopping between dimensions, eating stars, blowing up planets, harboring the ultimate embodiment of evil, or trash compacting - it needs to be GIANT. Cameras pan along it forever. Its shape should probably have a few spines, and at least one region covered in strange glyphs. It should be completely unclear how such an object could move, and at some point it should be weaponized. Bonus points if it gets blown up or taken over by pirates.
2. Set the action in motion by plunging us into the middle of an extremely complicated astropolitical regime change.
A massive political system, comprised of hundreds of planets and coalitions, has discovered an ancient alien artifact that plunges them into war that's waged on a thousand shorelines connected by wormholes and dimensional portals. Or: Six different people, and their hordes of scheming alien spies, are vying for the seat of Galactic Emperor. Now one of them has altered the timeline. Could it have been caused by this strange venom from a creature believed to be legendary, and whose secret will require a quest to worlds uncharted?
3. A scrappy group of humans should be part of a rebellion that's hidden on a cool-looking moon or tricked-out asteroid.
Rebel groups never hide in apartments. They always have amazing underground hideaways or hidden airborne platforms on an exotic place with bizarro weather. Eventually the Big Bads and the Rebels will blow the fuck out of each other but not until after we've seen at least ten freaky locals near the rebel hideout and like six cool underground moon bases, which we'll reach via a series of briefly-seen but outrageously weird images of upsidown cities hovering over purple clouds.
4. There must be an enormous mothership (which must be referred to as a mothership or maybe a base ship), and it must be attacked by a bunch of tiny fighter ships.
Don't forget the tense crosstalk between the fighters, including but not limited to use of nicknames, use of made-up "futuristic" curse words, and use of breathing noises intended to sound like somebody using an oxygen tank. One of the fighters should engage in a reckless act, like singlehandedly taking down the mothership or flying really low above it to get intelligence.
5. Always fill your spaceships and intergalactic ports with random background aliens and weird-faced creatures.
Just don't allow any of them to have lead roles. We want to see the shiny green slavegirls and pimply hosenoses in the background, but please tell them to shut up when the humans enter the frame. Aliens are great as long as they are helping the people of Earth, but they should know their place: As sidekicks and extras. Aliens who look exactly like humans - except for maybe some pointy ears or fetishistically-sculpted bodies - are allowed to be important supporting characters.
6. Your heroes should always revisit the sites of old battles, the locations of terrible accidents, and the regions of space where their people were wiped from the face of the universe. But only if they don't want to.
Being reluctant to save the day is shorthand for so many space operatic things like having a dark past or conflicted motivations. But the beauty part is that if you have a reluctant hero you don't actually have to account for any of those pesky character traits. You just have him say, "No, you can't make me go." And then the authority figure says, "Look, it's your last job. We need you. You're the only one who knows about this terrible region of space associated with some bad thing of yore." And the hero says, "Fine. But I don't want to." Instant Deep Meaning.
7. If there is a male bad guy, he should have a ripped body or amazing weapons. If there is a female bad guy, she should have a high, sparkly collar or a sidekick named something like Tigerman.
Enough said.
8. There should be at least three types of weapon and three types of spaceship, each of which will be given a name that is used repeatedly.
"Sir, we've got the pulse cannon ready on the Shark." "Well, power up the plasma rifles on the Heavy Tigers." "Cadet, grab your rez gun and get your ass onto that Starmasher!"
9. There should be a captain. If there is not a captain, there should be a special agent. If there is not a special agent, there should be a cadet with a future. If there is no cadet with a future, there should be a mercenary with a dark past.
If there is no mercenary with a dark past, there should be a wisecracking stowaway. If there is no wisecracking stowaway, there should be a witch. If there is no witch, there should be a scientist. If there is no scientist, just remake Spaceballs.
10. Somebody wise should predict something, but nobody will pay attention or be able to understand the prediction.
Nevertheless, words from the prediction will be repeated over and over throughout the space opera, in echoing voiceovers that grow increasingly portentous as the ending draws nigh.
BONUS RULE!
Male heroes get laid. Female heroes fall in love in a way that tests their loyalties. Aliens yearn tragically, or develop strange relationships with machines that we laugh at. Don't even think about robots.
This io9 Flashback originally ran in 2009.