PhotoPrepare for a repair
Duplicate the image layer before a destructive retouch. Zoom to 100% to judge edges and texture. Use a brush only slightly larger than the blemish and make short strokes. Compare frequently by toggling visibility; a repair that looks smooth at a high zoom can look artificial at normal viewing size.
Check the active layer, selection and mask-editing state first. Opacity changes stroke strength and hardness changes its edge. The Brush and Eraser remember their own sizes.
Choose a healing tool
Spot Healing is a starting point for small blemishes. Healing Brush gives more control over the source used for the repair; follow its source-sampling prompt before painting. Patch is useful for repairing an area from another region. Remove and Content-Aware Move attempt larger content-aware changes and should always be inspected for repeated textures or invented-looking edges.
No repair tool can know exactly what was hidden behind an object. Around faces, text, fences and repeating patterns, use smaller regions and undo poor results rather than repeatedly blurring the same spot.
Evaluate the result
Inspect the repair both close up and at fit-to-window. Look for mismatched brightness, repeating patterns, halos and softened edges. Keep the original underneath until the image is finished, then save the layered PSD before exporting.