Concentrate when your good enough, to really get the edges in certain areas, nice and crisp. It will add a bit of realism to the picture.
And its alot of greys. Colors of owls are never fully grey. If alot of stuff was grey, then it would be a black and white painting with a drop of color. They are just really variants of really dark colors. Mostly its dark brown or a dark blue. I think in a way its ok to start out grey, and you can count as an underpanting (via a value/greyscalepainting). Then overlay colors on top.
Yes, I know. My point still stands that colors in a picture are usually never just a pure black or even grey in a sense. It makes the picture look flat if your going for colors. The face of the owl, is a bluish tone of brown. I can also guess its a bit desaturated because this is taken during a cloudy day.
If your really getting close to the reference, it needs alot more contrast. Don't do the details first, block in the shapes generically (even values) then go back and do the detailing.
Just draw, draw again and draw some more. Eventually you will start to see things that you don't like about your older work and then it's possible to determine what your weaknesses are. Also, you don't really need tutorials. I feel like keeping a unique art style may be more important than learning fast (because tutorials do quicken learning).
Doesn't look too bad for the first digital painting.
But you should start off with the basics first. Get the proportions down (correctly! This step can take days, but if it takes so long, then it's okay. A painting where the proportions are wrong is a bigger fail then a painting that isn't detailed as one of the old masters) and then focus on the general shapes. Squint your eyes and block in the first values and slowly make smaller and smaller shapes. So you try to build your way up from rough to detailed.
And the most important thing: Stay away from custom brushes as long as you are a beginner. They make the whole painting look "amateur-ish" because you didn't really know where to use them. You just waned to use them
This may be a lot of critique but just start simple and don't let yourself overhelm by all the stuff you can do digital. Good luck dude and just keep going, no matter what other people say!