So I'm just starting out with doing manes and tails and so I messed around and made this this morning, what do you guys think?.

I know I have to work on drawing out the mane (I'm not a very good drawer when it comes to that lol) but what else could I work on.

Also I will be adding credits to it as well

Not a bad start! Definitely play around with the brush settings to see what you can get. Also, on the tail did you leave a chunk of the hair from the original picture? I can see something behind the hair that you drew. When you can make manes and tails, you should probably make it so that it's not visible. It could use more dimension to the hair, try adding shadows and highlights, that should help!

Edit: add some hair flyaways and breakup some of the patches to make it look more natural