Linking Adventures
Using similar locations and related creatures helps you form connections between disparate adventures. For example, you might have the players explore a frozen corporate outpost on Vesk-7 early on, then later travel to an icy plane filled with more difficult challenges that can be overcome using knowledge they've previously developed. Likewise, glitch gremlins might be tough enemies for your group at low levels, but as the PCs attain higher levels and the gremlins become mere minions of a powerful fey technomancer, the players feel a sense of progression. Over time, the players feel like their characters are becoming experts at negotiating with Veskarium soldiers, navigating the stars, battling daemons, navigating the Drift, or dealing with whatever the recurring elements are.
Consider how each adventure's theme plays into the campaign as a whole. You might want to keep similar or recurring themes, especially if each adventure is part of one overarching storyline. On the other hand, this can feel repetitive, and some groups prefer variety and seeing their characters play off of different situations. To convey shifting themes, you can show established parts of the world changing to reflect the new theme. For instance, if you're switching from a dystopian campaign to one with futuristic and fantasy elements, the PCs could buy their impounded starship back from an azrinaran oligarch on Apostae but then face magically controlled fungal constructs and corrupted Skyfire pairs on Triaxus after they arrive looking to join the legendary Skyfire Legion.