Training

First critique I've ever written yay!
I'll start with the good stuff <img src="e.deviantart.net/emoticons/b/b…" width="15" height="15" alt="" data-embed-type="emoticon" data-embed-id="366" title=" (Big Grin)"/>
what I really like it about this picture is the interesting angle of both cats, and the way you drew the background. The light shining down on the them is really nice. The way you colored the cats is great, and I especially love their faces. The positions they're in are very interesting, especially Ember.
Now for what I think you could improve on~
The line art is quite messy, and the coloring often covers up or goes out of the lines. Just take lots of time on the line art and for coloring, and make sure its on a different layer that's underneath the line art one, if that makes sense.
There are also some anatomy/perspective issues - Roach's mouth/jaw perspective looks kind of off, and her face in general seems a bit... flat. The arc of her back is not quite right either, and I would suggest looking at some reference photos for her paws. Although I love the way her tail is sweeping behind her, cat's tails are actually a lot shorter.
I also think that putting a bit more emphasis on the shading could really make the cats pop <img src="e.deviantart.net/emoticons/b/b…" width="15" height="15" alt="" data-embed-type="emoticon" data-embed-id="366" title=" (Big Grin)"/>

So to sum that all up, I love the way the picture is set up, the composition, lighting and shading are all great, but I think it would really help to look at some references of real cats and work on the line art!

Hope that helps! <img src="e.deviantart.net/emoticons/h/h…" width="17" height="23" alt="" data-embed-type="emoticon" data-embed-id="599" title=""/>