Looking for aliens in outer space is a fool's errand. If you do find them, it means they were so sophisticated that they sent complex messages across light years of space, and therefore are more likely to enslave us than empower us. If they are primitive life forms, they may infect us in ways yet unknown. So why bother?
If in fact you do want to find extraterrestrial beings, look no farther than inside yourself. They are already here. Here is my reasoning:
Sixty tons of space dust falls on planet Earth each day.  Recent studies have demonstrated that certain life forms can survive the passage through the atmosphere, and even reproduce once on Earth.  These studies were done by loading fragments of DNA and spores into rocks, and mounting them onto exterior of rockets launched into space and returned to earth.
Twenty percent of the DNA in your nose, and 40-50 percent of the DNA in your gut, codes for life forms as yet undiscovered.  When we realize that bacteria were only recognized in the 1670s -- and understood as recently 1860 by Pasteur, with viruses not recognized until 1892, by Dmitry Ivanovsky -- we understand that we are just at the beginning of understanding life.
We understand as little about our own microbiome as we do about the vast oceans surrounding us. They too host enormous numbers of yet-to-be-discovered life forms, some living near extremely hot vents of volcanic material erupting from the inner earth. Did these heat resistant forms come from Earth, or land on earth?
Most likely, the life forms landing each day on the Earth and its oceans are inhaled into every living being -- and survive in some. So we are both earthly and alien. 
Using our resources to look within and around ourselves first -- to understand who we are now, and to preserve our collective future -- is far more likely to benefit the survival of our species than searching for other solar systems and planets. Our oceans and our bodies are as unknown as outer space, and far more beneficially explored. 
In my own experience, looking deeply into the stem cells within us and understanding their influence on healing injured tissues has yielded an opening to entire world of novel therapeutic possibilities. I've found that the intricate structure of the human knee, with its meniscus, articular cartilage and ligaments, is as complex and surprising as any planetary system orbiting a distant star.
And even if we do find other worlds, they are unlikely to be as heavenly as our own Earth. Finally, consider this: While we must beware of what (or who) we might run into there, we can be ecstatic about what we may find here.
 Inferring the global cosmic dust influx to the Earth's atmosphere from lidar observations of the vertical flux of mesospheric Na Chester S. Gardner, Alan Z. Liu, D. R. Marsh, Wuhu Feng, J. M. C. Plane. First published: 18 September 2014 http://onlinelibrary.wiley.com/doi/10.1002/2014JA020383/abstract
 http://www.scientificamerican.com/article/dna-can-survive-reentry-from-space/ DNA Can Survive Reentry from Space By Dina Fine Maron | November 26, 2014