Critique Please!

I haven't drawn any pons lately but I do have a few pieces I would like some thoughts and advice on! In the order of oldest to latest (links b/c they a big mess of pixels);

Andy: http://img06.deviantart.net/cbeb/i/2016/152/e/d/ain_t_life_grand_by_pommatre-da4mb5e.jpg

Cricket: http://orig08.deviantart.net/c456/f/2016/161/9/0/4am_by_pommatre-da5oh9f.png

Mary: http://orig15.deviantart.net/394d/f/2016/161/d/5/3pm_by_pommatre-da5qjgn.jpg

((specifically I would like to hear some tips on skin tones and expression and definitely how to maybe create depth/render efficiently and minimally))

thanks guys (✿◠‿◠)

I love these! Maybe just work on your anatomy :)