Sometimes images may not have the vibrance and color that you would wish for in an image,. Though there are many ways to do this the easiest is doing this after converting images to Lab Mode. Then Curves and Unsharp Mask can do the rest. This works for all images.
This is the processed image. The original is below.
I will be using this free stock image. You will find it here
It belongs to ThrashDrummer
Step 1 : After opening the image in Photoshop. Go to Mode>Lab Color.
Step 2 : Press CTRL+J to duplicate the Background Layer to Layer 1.
Step 3 : Click the New Fill or Adjustment Layer button and click on Curves. The Curves Adjustment Layer opens.
In the Curves you see that there are three channels in the drop down menu -- Lightness, a and b.
Step 4 : Click on the a channel.
Step 5 : Drag the top of the diagonal one square left and the bottom one square right as shown.
The image looks like this. The colors look unreal.
Step 6 : Now click on the b channel.
Step 7 : Do the same as in Step 6.
The image looks like this. The colors are over saturated.
Step 8 : Click on Layer 1.
Step 9 : Go over to the Channels pallete and click on the Lightness channel.
Step 10 : Go to Filter>Sharpen>Unsharp Mask.
Step 11 : Keep the Threshold at 9 levels, Adjust the Radius to between 2.4 and 3.5 or a bit more and increase the Amount from 0 to maybe 150%. These values are not hard and fast. It will depend on your image. Click OK. You can use the hand tool to see an area you wish on the image. Here I wish to see the face.
Step 12 : Click on the Lab channel. Then click back on the Layers palette.
The image looks like this. The colors are a bit too strong.
Step 13 : Click on Curves 1 Layer. Reduce the Opacity suitable. I have reduced it to 60%.
The finished image. Other photoshop tutorials are here.