Since you asked for critique:

The best piece of advice I can give you is to stop using bases. I used bases when I was around your age and nothing will stunt your growth as an artist more than relying on bases. I understand that you may not currently have the skills or materials to produce great digital art, but using bases will only cause whatever skill you have to halt growing. Not to mention the fact that most bases are just traces/rips from animation or other artists' works. The best way to improve is to start by going back to the basics of art. Look at tutorials and lessons online, rent or borrow art text books from the library, or even take art classes if you're serious about becoming an artist. It may take some time and practice before you can comfortably move onto the subjects you like, but it's important and necessary to start from the bottom.

But I digress. Onto the actual image:

White backgrounds rarely do an image any good. Even a simple background color or geometric design can help a piece seem more coherent. When a figure is just floating on a white background, it's clear we're just looking at a drawing. The viewer is not being drawn in or enticed by the image.

The placement and size of the image is also troublesome. One of the fundamentals of good artwork is having a focal point - a place on the image where the eye is drawn to - and this image does not have one. Look up the Rule of Thirds for a better explanation on focal points and where to place them. Also, by situating the figure up against the very edge of the image the eye is drawn outside of the piece and it detracts greatly from the work.

On a technical level as pixel art, it leaves much to be desired. Obviously, most of the work was already done with the base. The only additions I can see would be the coloring, hair, and back marking. The coloring is basic, with no shading present. The colors chosen are rather dull and do not work together well. Many of the colors look very unnatural, such as the bright pink of the paws, stark black of the hair and tail puff, and the eyes. Bright colors /can/ work well together, but they have to have coherence, and stark colors do not go well with earth tones like the tan of the fur.

The hair could be greatly improved by giving the hair more shape and by fixing the coloring. The hair on top of the head seems to have no physical shape, laying like a perfectly flat piece of fabric on the head. Even very fine hair has shape and does not perfectly conform to the head. Hair also isn't usually one solid mass. Because it is made up of individual strands, and by larger locks, hair usually separates into more distinct chunks. Breaking up the hair from one solid mass would help it seem more realistic, as would adding a few errant strands.

Rarely do solid black things ever appear perfectly black. Most black colors are either deep hues of other colors like green or blue, or are very dark grey. Using solid black only works in very specific situations, and hair would not be one of them, especially when no highlights are present and black line art is used. Using a dark grey or deep color would still give the appearance of black hair, but leave you more able to give the hair shape by using lines.

Finally, the purple marking on the back does not seem to fit the design at all. Like I stated earlier, bold colors do not typically go well with more neutral ones, and the contrast is jarring. By toning down the saturation on the purple in images, you might still be able to get it to fit with the other colors. However, just using the paint bucket to fill in the marking will not give good results. Markings do not have perfect lines on real fur, especially longer fur, so you could improve the marking by breaking up the edges like you can see with the line between the belly and upper fur.

Overall, I don't think this piece shows what potential you have. Coming from someone who used bases for far too long, I saw little improvement until I stopped relying on the works of others and started studying and practicing on my own. Good luck, and I hope you found this critique useful.