Q: How do you keep your story from getting too complex?
A: Here, meet my critique partners. Aren’t they amazing?
See, as a writer, I’m still learning how to keep things simple, and by simple I mean being able to hold the whole story and all its moving pieces in my mind for that final quartile, so I can wrap up the whole yummy burrito. An overstuffed burrito is a ruined white shirt, and I have…well, let’s say I have a guacamole problem. However, that’s where my amazing crit partners come in.
My CPs are kind of alpha readers who also know SO much more than I do about craft. They margin-note anything that's confusing or well-that-came-outta-nowhere or interesting-but-never-mentioned-again. Those margin flags typically indicate I have a whole back story for that element and love it to bits and really, really want to use it to complicate matters, but it isn't useful to this story/character/moment, and so it needs to go. For instance, plot threads concerning Mari’s mom and Garrett’s super powers and the oblique, giggletastic Terminator fan-service references? Gone. Snipped. Fixed. Streamlined. Thank you, SuperCPs.
In sum, my advice to everyone attempting to KISS (we all know the acronym, yes?): get some alpha reader/crit partners who know their stuff and aren’t hesitant to call you on your over-complicated crud.
(Note: It's tricky but not really hard to build good CP relationships. I met one CP because we were both writing a lot of self-indulgent Tolkien fanfiction a million years ago, one through a romance-writing professional organization that gets together in person monthly, and one because we slept together at a local writing retreat, which isn't nearly as salacious as it sounds. If you gut-flinch at the thought of going face-to-face with other writers in person, Critters might be a nice place to meet SFF-minded folk online. If you're a member of the RWA FF&P chapter, they have a mudpuddle that kind of functions as a CP dating service for folks writing SFR and PNR. Make sure to trade sample chapters before you get hitched for the whole manuscript, and also try to hook up with someone who is just a little bit ahead of you in craft knowledge.)
Oh! And one addendum from the former-litcrit-student in my head: it also probably helps to focus on a tiny, tiny group of POV characters – one, if you can get away with it – and their goals, motivations, and conflicts. If a worldbuilding piece doesn’t affect your protag, ditch it. The only stakes a reader is going to care about are those that directly affect your POV character's internal journey.