Whilst I do find Mine-Imator somewhat non-professional, I did use to be a big user...and one of the bigger, better...but un-noticed riggers for it...
Since my use, Mine-Imator has changed drastically...and, unfortunately, my rigs don't work their best on 1.0.0.

These are fairly good renders...so well done on your part for that.
My tips for you on making better renders is: Lighting. This is one of your most important tools in making a render or animation. Make sure to get the lighting just right or it can ruin the whole image. Second, Pose. Having your characters in a good and pleasing pose is always necessary. Last, I would work on facial expression. Try to make your character look at what's happening in the image with a correct expression. To find the best expression, you may need to take a few 'selfies' of yourself making different expressions. And as a last little tip, background. You need a good place for your character to interact with and be in.

I look forward to seeing you improve with your work.

-Potato

(Ps: These forms of images are typically referred to as 'renders' and not 'pictures' or 'images'. Sorry if I confused you a little.)

Nice!  :D