Identifying Layers

If you’re ambitious with your collages, then you’ll be familiar with this problem: meaningful layer names are often neglected during the creative process. This can result in layer names like “Layer 4” and “Layer 5 Copy 2,” which are not very helpful when you need to quickly identify the contents of a layer.
Photoshop offers a number of solutions for our laziness. For example, you can click on the element you want to select by using the “Move tool” and holding the right mouse key; you’ll see which layer contents are below the tool. Photoshop will display a list in a drop-down menu, from which you can easily select the desired element.

 Right click with the Move tool
 
Control/Command + left-click with the Move tool selected and, in most cases, you’ll select the corresponding layer of the element that your mouse is over (unless Photoshop can’t distinguish between the multiple layers).
You could also Control/Command + left-click on a layer’s miniature icon to get a selection of the content of that layer. The marching ants will show you what is on that layer and where it is.
Another option is to click on the Layer palette’s Options icon, in the top-right corner, and select “Layers Palette Options.” From here you can adjust the size of the layer’s miniature preview and concentrate the miniature’s content to the layer’s bounds, which should cut down on future guesswork when it comes to layer contents.

 Layers Palette options