Hey Pavel, thought I'd throw some thoughts in on your cartooning... Thus far given you've not done this kinda thing, you're off to a steady start! The animals all have a certain sort of charm, but I really think you could push their poses, their personality and their setting more to tell a story. I always get the feeling from looking at the works of companies like Pixar and dreamworks that even their simplest sketches set out to tell you something unique about their characters, and when it comes to their more polished illustrations, nothing is left to chance... the last detail of body language and shape all contributes towards giving the viewer a real sense of who the character is. And I kind of feel like this is what's missing from your work thus far... The wolf bear and owl are cool but they're all in fairly standard poses with fairly tame expressions (the owl is pushing this more than the other two). I'd say think on how you can get certain features to push the personality of the creature, make them a little more human so people can relate to them more. Take the owl for example... what if you made his eyes much smaller, or gave him huge bottle-thick glasses. Push his squint so it's even more caricatured than it already is. Right now he feels more like he's just seen a friend flying through a murky night and he's keeping an eye out to see if he passes by again, rather than is really straining to see anything at all. Maybe a different camera angle would allow you to show off the craning of the neck better?
I'd say before you go into fully coloured pieces, try just sketching the same character numerous times on a page... get a feel for the shapes of him, of what kind of personality he has, then give him a story, an interesting snippet in time. The owl might be blind, but what if he were just on the bottom branch of a tree barely off the ground? Or if he were sitting on the horn of a deer, mistaking it for a branch?
I've done you a paintover of the bear to try and illustrate what I mean... By tweaking his pose to be sitting down it suggests he's been waiting by the hive for a while. I've rounded things off to give him a dumpier, goofier feel, and fleshed out his cheeks a little - all things that might add to illusion he's probably a greedy beggar. I've tilted his head, made his smile more obvious and added dark patches around his eyes. I made the whites of his eyes more grey and reapplied the highlight to give them more life (the pure white was killing it), and I've given him very subtle eyebrows just above to suggest a slightly expectant expression. Adding the teeny bee and lifting his paw off the ground suggests he might just paw either the bee or the hive in a second. - there's a number of possible stories going on in the image, up to the viewer to decide what kind of guy this bear is, within the personality the shapes and expression have given him already.
* simplified the background and painted out more of the lines to give the image consistency.
* Added more of a rim light to the bear to pop him out
* added cast shadows from the trees
* darkened the foliage a lot