Quick Fix
Quick ways to improve the overall appearance of an image.

Do it for me 1. Choose Image > Rotate > Straighten and Crop to adjust your image if needed. Otherwise skip to step 2.
Do it for me 2. Choose Enhance > Auto Contrast to improve the overall contrast and mixture of color.
Do it for me 3. Choose Filter > Sharpen > Unsharp Mask to sharpen the edges in your image.
4. Select Preview to see the difference between the adjusted image and the original.
5. Drag the Amount, Radius, and Threshold sliders until you see an improvement.

The Amount indicates how much to increase the contrast of pixels.

The Radius determines the number of pixels surrounding the edge pixels that affect the sharpening.

The Threshold indicates how different the sharpened pixels must be from the surrounding area before they are affected by the filter.

6. When you are satisfied with the result, click OK.