As you may have noticed, Photoshop has a very wide range of tools and dialogue boxes. To master photo retouching, you may only need a hand full of methods to achieve professional results.
Essential tools of the trade
The Clone Stamp Tool
This is probably the most heavily used retouching tool, so it is well worth taking your time with the Clone Stamp and perfect your technique. Here is a detailed article on the Clone Stamp Tool.
The Heal tool
This tool is almost the same as the Clone Stamp in that it is used to duplicate pixel information from source via a brush. The only real difference is that the Heal tool will adapt the duplicated pixel information, blending it via the brush. An excellent tool for the retouching skin or skies and areas of continual texture.
This will sharpen your image. To load the Unsharp Mask dialogue box: (menu)->Filter->Sharpen->Unsharp mask. Generally, you can keep the ‘Radius’ on one and the Threshold on zero. Slide the ‘Amount’ percentage to get the desired effect.
Tip: Always apply unsharp-mask before you start restoration and clean up. Remember to vary the techniques that you have learnt so far.
Levels are used to improve contrast, light and dark and colour either as part of a selection, layer or the entire image. To load the Levels dialogue box: (menu)->Image->Adjustments->Levels or CTRL+L. For more information about levels, please read: Fixing contrast – black & white, or Photoshop Levels – Colour.
The basic steps of photo retouching
Here is an ordered approached to photo retouching.
Tip: Remember to save every 10 minutes or so to ensure against loss. Always keep a backup of your original image/scan in case it all goes horribly wrong.
Crop image: I recommend doing this at the very start to ensure an accurate reading of the tonal information when performing Levels. Cropping will also draw focus on the task ahead as well as bring the le size down.
Remove non-photographic elements: Remove any ink blots, major scratches, borders or marks and stains. Again, this will help when performing Levels.
Apply Unsharp Mask: Before cleaning any general dust and scratches from your photograph, you should firstly apply Unsharp Mark. Make sure that you don’t over do it. Over sharpening will result in halation.
Perform levels: With all of the dirt, blemishes and any unwanted objects removed from your image, now is the best time to perform Levels.
Comb out the dirt: Using CTRL+ and CTRL-, zoom in at between 100-200% and scrutinize your image for any remaining blemishes. Use the Clone Stamp tool in the trickiest areas and the Spot or Heal tool in areas of continuous texture. You can also try the (menu)->Filter->Noise->Dust & Scratches filter to clean up larger areas. You will have to do this in conjunction with a selection.
Rebuild any obliterated areas: Use the Clone Stamp tool to rebuild missing or badly damaged regions.
Final levels: Apply your Levels for the last time. You’ll be amazed how quickly the histogram can change.
Lighten or darken unbalanced lighting: Make adjustments via Levels within feathered selections. For smaller areas, you can use the dodge and burn tools.