A good teacher, guide, or mentor may be able to give some helpful advice, point you in the right direction, and warn you against the pitfalls, but you must walk the road by yourself, and there are no shortcuts.
Writers are self-made.
The instinctive response is to clap on a helmet and start digging a trench. They should not be native to a studio prop room. The difficulty, of course, is in deciding how far to depart from intuitively credible Earthly life when depicting natives of other worlds. Too little, and the aliens might as well be humans with corrugated foreheads. Too much, and they become ridiculous.