hi guys well it’s my first post here (i think :o) and i’m new in the modelling.
i have a very bad imagination (very very bad imagination) . so i tried to create a creature.
i started wuth it and i’m quit happy with the results but i’m stuck in how shall be the mouth and the nose .
so here is the unfinished model plz give me ideas about the mouth and nose (i kind of want it scary)
and maybe advises of mistakes .
Good start 
My advice would be to step down a few subdivision levels, save a morph target, and just experiment. That’s the fun of ZBrush, it’s pretty forgiving and super fun to just noodle around in. That or just bust out a pencil and paper and draw until you come up with something.
My advise: being fairly new to zbrush and the modeling world, i’d suggest you start from the beginning(obviouslylol)…It’s fun making monsters out of your imagination, but it will be more helpfull to try and re-create from real reference.
firstly, try to model humans, full body or just parts (head, hands etc…) and progressively getting to make a full figure. Try to learn what is going on under the skin, no other way to get things more believable (monsters included)
You can then start on animals, learning their anatomy is the best way to build up your creativity, starting by just copying motehr nature, and then eventually coming up with creatures of your own.
Use reference as much as you can, and if there is a model or a picture out there that you like, try to re-create it, it will teach you a lot,getting closer to figure what the other artist tryed to do and the challenges that he faced…
it takes time before being able to “invent” new concepts of characters, i’m far from being capable to do that, and ive been doing this for years lol
Good luck 
for the nose part, he looks like a werewolf to me, so try to put him a dog nose or maybe a lion ? already done before, but as i said, you need to start somewhere