Sponge Tool - use to saturate or desaturate pixels. Useful to intensify or tone down specific areas with greater detail and precision. (This tool is found in the tool palette along with the Burn and Dodge Tool.)

Healing Brush Tool - used like the clone tool, but this tool is most effective with forms that are friendly to freehand work. It clones, but adapts the sample according to the texture of the area being healed. To use it, select it from the tool palette, then select the area from where you want to sample (apple/click) and then adjust the area you desire.

Patch Tool - Similar to the Healing Tool, only it does not sample color, only patterns. To use this tool, select the area you want to adjust or manipulate, then press your mouse and drag out to the area from where you want to clone.

Measure Tool - used for measuring specific areas of your document. This tool is found in the tool palette along with the Eyedropper Tool and the Color Sampler Tool.

Measuring guidelines - These are useful to line up elements precisely. To access this feature, make sure you have Rulers set to visible: at the top menu select View > Rulers, then go to the Rulers' edge and drag as many horizontal and vertical lines as needed. To hide them: View > Show > Rulers (will deselect automatically, when already checked).

Grid - Useful to help you measure your layout. To access it, at the top menu select View > Show > Grid.

To align layers, create Guidelines according to your desired measurements, then create a selection with your Marquee Tool; make sure that one of the sides of the Marquee is lined up right on top of the Guideline to which you want to align your layers to. Leaving the marquee tool active, choose the Selection Tool. the alignments options at the top of the Selection Tool menu will become enabled. Align your layers as desired by clicking on the tools of your choice for vertical, or horizontal alignments, etc. You may go back and forth between layers by selecting them on the layers palette, as long as they are within the marquee tool's selection.