All of our conceptions of what aliens might be like are usually human bodies with heads or faces an artistic mix between human and other animals of earth.
Their civilisations are usually very similar to our own.
We must first see alien life to be able to imagine it.
We have pretty much no idea.
So it is fertile ground for speculation, and that is exactly what this section is all about.
Even with low end estimates for the probability of life occurring on a planet, with so many galaxies in the universe you still end up with estimates of civilisations in the hundreds of billions, and for more basic life it is many magnitudes higher than that.
With quantities like these, some truly crazy things must be around. We are free to speculate what lies deep in the universe beyond our ability to detect, like dragons and monsters on the edge of an ancient map.
There is also considerable overlap in this section with speculation on what the future of humanity may hold.
Perhap you can use Animal strategies use this to speculate on Alien life, based on strategic requirements.
(I.e. "Being militarily strong would be advantageous for an alien civilisation", as opposed to "E.T. must have some kind of an armed forces" - like Sharing the Universe by Seth Shostak)
Aliens that communicate through flashes of light- like we do with flashes of sound. It's intricate too. And it doesn't have to be visible light either.
If they are spacefaring, surely they must include strong elements of science and engineering.
H.P. Lovecraft, The Silver Key
When Randolph Carter was thirty he lost the key of the gate of dreams. Prior to that time he had made up for the prosiness of life by nightly excursions to strange and ancient cities beyond space, and lovely, unbelievable garden lands across ethereal seas; but as middle age hardened upon him he felt these liberties slipping away little by little, until at last he was cut off altogether. No more could his galleys sail up the river Oukranos past the gilded spires of Thran, or his elephant caravans tramp through perfumed jungles in Kled, where forgotten palaces with veined ivory columns sleep lovely and unbroken under the moon.