Okay so I'm going to be honest and do my best to critique. Oh boy lets see how I do.
First off it's a really good start, it doesn't look flat with the 4 legs on one side, you can tell it has depth.
The head needs some work, based on the ear positions you should be able to see part of the cheek and the other eye, and a more cocked snout. Like it's more so looking around towards you. You don't want to seal off the shoulder or front legs from the- rest of the body, it does connect to the torso. The front legs look pretty good, appears like there is weight on them. The feet need some work. Animals do have toes ^^ and they do show, even on very dark coloration.
The back arches a little to much, making it so the back legs look longer then the front. (I have this issue sometimes myself.) Also the tail is an extension of the spine, so it will set in between the hind quarters. The farthest back leg looks really good, the front rear leg looks wonky.
I can't color with marker for the life of me, so I'm useless there. I can say when your inking be confident, if you make a screw up don't worry, just flare it out or something to make it look like ruffled fur.
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All in all it's a good start. And I hope what I said helps you, I look forward to seeing more art from you.