Sometimes when I am arranging the elements on my scrapbook page, I find the shadow layer styles don't look right. I've learned another way to create shadows, putting them on their own layer.
Here I am beginning a layout in which I placed a curvy piece of paper at the bottom.
To create my own shadow layer, first I duplicated the wavy paper layer, by hitting Control/Command-J. Then I clicked on the bottom wavy paper in the layers palette to select that layer. We want the shadow underneath, of course. To turn the layer into a shadow, I type Control/Command-U to open the Hue/Saturation dialogue box.
In the Hue/Saturation box, I dragged the Lightness slider all the way to the left. You can see this in the screen shot below. Notice there doesn't appear to be any change on my layout yet, because the layer I'm working on is hidden behind another the same size and shape. However, you can see in the layers palette that the layer has turned black.
After pressing OK in the Hue/Saturation dialogue box, keeping the same layer selected, I chose Blur>Gaussian Blur from the Filter program menu. In the Gaussian Blur dialogue box we can adjust the radius of the blur with a slider. I adjusted it until it looked good to my eye.
It is advantageous to have shadows on a separate layer. You can alter their color with that Hue/Saturation dialogue box. Shadows often have some color from the objects casting them. You can transform the shape of a shadow independently from it's object if it's on its own layer, which leads to some interesting creative effects. This last idea i'm still learning so I don't have a sample.
If you use this technique, link us up to it in the comments. Here's my layout, using Jeanine's kit, Twilight Snowfall.