Hi, Subbie.
I'm a science fiction writer, and I hope to publish someday, so I'll keep the details of my trade secrets to myself until then.
But, I did want to suggest that I consider it most likely that alien life will follow most of the same patterns that we see life follow here.
There are two predominant trends in sci fi that I've seen: the Star Trek way, in which aliens are just humans with make-up or a mask on; and the new school, in which they try to make everything they can completely different from the way it is on Earth.
For instance:
I say carbon and water is what we'll find most life is made of (though some alternatives may be likely).
Life will generally have cells, or something like them.
Life will generally evolve in Darwinian fashion.
Broad divisions equivalent to plants and animals will be common.
We'll probably see a lot of general analogy with Earth life in terms of anatomical features (e.g., I think cephalization may be particularly common in "advanced" organisms; bilateral symmetry will be common in terrestrial organisms).
-Bluejay (a.k.a. Mantis, Thylacosmilus)
Darwin loves you.