I take an interest in species if they're like one of the following, I suppose:

• Warrior races (the 14 year old boy in me will never die!!) Both primitive, barbaric ones and heavily disciplined, more advanced ones are neat.

• Surreal creatures that aren't just animals or insects with arms and legs, or golems or something like that -- something that needs proper description. It's even better if I've never seen anything like it before.

• Either blue and orange morality, or they're "bad", but they see themselves as good and there's adequate explanation for why. No one really wants to think they're the bad guys, or that they're doing something wrong, outside of those who are mentally ill

• Cute races ;3 Easy if your setting's supposed to have an anime aesthetic.

• The more that you've described their culture and made it not just sound like an analogue or a mishmash of real world cultures, the better. I am guilty of not doing this enough, but it is there, running around in my mind somewhere. I've tried to keep descriptions of each species and homelands short in the .txt files so I don't go crazy, but eventually they may get longer and then they'll certainly have more life. My sci-fi setting is going to have zero analogues outside of the humans, which will certainly be a challenge.

As for my species and my preferred methods, I use a lot of really generic species for my medieval fantasy setting, but my sci-fi setting has plenty of aliens who aren't just anthropomorphic animals, and not a single elf or dwarf is present there.