Well bro, why not highlighting the arms of the fireball guy...Use some soft orange highlight on those in order to get the real fire effect =D
Also I'd give a slighty contrast to the bottle of the second dude, the third gay, I rather use more intaturated colors to make a better show off the arms
On the sneezing dog, I would probably work more on it...try some furry effects or something, and his right ear should be fixed since there's no way of being on that rotational positon
LEt's see some upgrades =D
btw, they are generally nice ideas =D