Well considering it being your first, I'd say it's not too bad. You could go through and clean up the lines to better define the shape of certain things, and some of your shading, like on his left hand, makes it not stick out as much, it looks like it's almost part of his chest.

And also, since you did just start out, I'd say to start out on smaller pieces. That's what most people do. That's how I did it. I still don't dare do something big yet to be honest. I don't have enough patience to do something big.

Keep it up though, I'd say work on that avatar now. Since they are 64x64 pixels, and that's pretty small compared to this.