This is such a common thing that I don't think I really have to point it out to anyone, but here it is, a phenomenon common to both science fiction and fantasy to varying degrees:
People pick established species on which to base their alien races, and established time periods on which to base their technology.
There are a lot of great reasons to do this. One excellent reason is an idea I talked about earlier, that of the conceptual "set." If you pick a preexisting set of characteristics for an alien and its technology, one that people are familiar with, then readers will not have to work as hard and they can use their instinctive expectations to guide them in understanding the story. A related reason is that the alien and its behavior will seem more "natural" if you match behavior to species and physiology and extrapolate it into the realm of culture.
On the other hand, as a writer you don't have to feel bound by these constraints. Not necessarily.
Sure, if you're pulling features of physiology, behavior, culture and technology from all over the place, it'll feel like a hodgepodge and not make any sense. That's not what I'm suggesting. I'm just saying that there are novel combinations of elements that can be used with internal consistency.
How do you go looking for a new way? I'd suggest starting with the understanding that physical setting influences physiology, and also influences culture, which also influences technology. As long as it's all connected, you can play around. Changing one aspect of physical setting will create ripples throughout the system. Changing an aspect of technology can be linked back to cultural preferences.
Let the elements of the world grow together organically and they can change each other. Let there be a reason for every departure from the set, and you may find your readers will trust you all the way.