How to make an Alien species, a guide I hope you may find useful.
This is not a definitive guide; nor are any of these hard-and-fast rules; these steps do not need to be done in any particular order; you can do do them any way you please, or even go back and forth from one to another; this is just a simple guide to one way of making an Alien species, that I hope you may find helpful.
Step 1: A basic idea
Get a basic idea of what you want your species to be like: are they active or indolent; united or divided; expansive or conservative?
Example: have an idea for an alien species called the Kyrzik: the Kyrzik are a greedy, avaricious specie