Beware? Yes, beware.

Photoshop is a tool. For some, it can be a great help. For others, it can be a hindrance.

What do I mean? Well, I'm not going to link to any specific works, because I don't want anyone to feel like I'm picking on them.

But think about it this way. You wouldn't use a screwdriver to pound in a nail, would you? And you wouldn't use a hammer to put in a screw, would you? Of course not. Hammers and screwdrivers are both great tools, but they do different things well.

Photoshop... has a lot of tools. But sometimes I see people trying to use these tools instead of developing their own talents. (At least, that's what it looks like to me.)

Folks, learn to color. I don't mean just take a crayon and scribble some color into a space on a sheet of paper. Seriously sit down and learn how to use color to convey what you want to convey. How should the texture of this section go? Which directions should my lines go? How should I transition from one color to the next? Where do the shadows and highlights go?

I see a lot of people out there using Photoshop to make up for their lack of color-thought. Photoshop makes colors look really good. It's like Crayons on steroids. AWESOME COLOR! So nice! But awesome Photoshop colors do not entirely make up for lack of thought in the process. A major problem I see in pictures like this is that people don't pay very good attention to the lights and darks. They just throw on some color, then throw in some random highlights and some random shadows, and yay, it looks good! But in the end you've got blobby shadows all over the place with no real rhyme or reason to them.

Does this mean folks should throw out their copies of Photoshop? NO! It just means that you have to keep in mind that even though what you get with it probably looks a lot better than what you would get with some colored pencils and paper, on a technical level, you haven't necessarily improved.

Now here: [link] is a nice little tutorial on using Photoshop to do shadows. It doesn't really matter whether you're doing your art with crayons, pencils, oils, spray paint, Photoshop, or whatever--so long as you learn to use your medium well and keep trying to advance your technical abilities. Don't use a particular medium to try to skip the learning process. While this tutorial is specific to photoshop, the basic underlying ideas it presents are pretty standard and would apply to shading in any medium--just the process would be different.

And here [link] is a much more detailed tutorial on some shading basics.

Good luck.