Hey Handro!
There's a lot to learn about hard surface / sci-fi design. Depending on how much you're used to consuming sci-fi and how comfortable you are at critiquing/improving those particular designs, your own aesthetic choices can come very naturally or, rather, be a huge struggle.
I recommend looking at this video. It is pretty much a bible-tier reference when it comes to good (and bad) design decisions in anything sci-fi. Armor, environments, weapons, whatever! it's all applicable, give it a go!
If you absorb some of the information in here, I'm sure you will be more critical of common sci-fi designs, and being able to sort out the good from the bad allows you to make better decisions yourself!