That the more you can imagine how your world works in terms of politics, the day-to-day life of ordinary people, the better, as you will write with confidence, having a clearer vision in your head. This really does show in your writing and will help readers willingly suspend disbelief so they enjoy your story. I think this is the biggest thing fantasy/sci-fi writers have to achieve. We logically know these worlds do not exist. We have to convince readers that in some dimension somewhere they could.
Avoid melodrama. It has always seemed fake to me. The drama you want should arise naturally out of your characters' personalities (i.e. someone like Eileen who is awkward and argumentative will keep finding themselves in hot water) and/or the way your world is run (is everyone happy or are there those plotting against the government so they take over your fictional world?).