Creating Creatures

Now when you are writing fiction( mostly fantasy) most people choose to create creatures to make their book more creative. When I was writing The Talking Cake, I made two different types of creatures.
Troll Demons: Like a mixture of minotaurs, and trolls. They work for the 4 witches, and we generally scary. Writing villian creatures is fairly easy because all you have to do is juts imagine the scariest thing ever and write it down
Maldovians: A group of viking-like people who terrorize Ireland( unfortunatly another place where The Talking Cake goes). They are friends with the 4 witches.
Now if you are trying to make your own creatures here is some stuff that might help.
1. What do they look like?
2. Do they have any weaknesses?
3. where do they live
4. Are they good or bad?
5. How do they act?

Now I know that answering these questions won't make it 100% that you can make creatures. Just use your imagination, and if you can't do that you can just combine common fairy-tale creatures together to make a new creature( like mer-fairy, or Angelmon).
-AM