The Clone Stamp tool is very powerful. Whether it’s used for image clean up, to add, or subtract elements, proper clone work is essential so the stamping is not obvious. Factors that readily show its misuse are improper hardness adjustment, obvious repetition in the cloned pattern, failure to use a proper sized brush, and failure to sample often and from many places.
Before you begin to use the clone stamp tool, I strongly recommend you enlarge the photo to at least 100%. This allows you to work with much greater precision as the enlarged view provides greater detail.
Step 1: Set the Hardness of the Brush: too hard a brush leaves behind tell tale signs of its shape. Too soft a brush leaves tell tale signs of out of focus artifacts. If you’re just beginning to use this tool, start with a brush hardness of 50% and experiment with varying degrees to get a feel. The size and hardness of the brush can be adjusted using the settings found in the Options Bar along the top of the Photoshop screen.
Step 2: Sample Often and From Many Places: Take a lot of samples from many adjacent locations to avoid creating a pattern that makes the cloning very obvious.
Step 3: Vary the Brush Size for the Task: Don’t try to accomplish all the cloning in one step using too big a brush. On the other hand, don’t use too small a brush creating extra time in front of the computer.