Basic Lighting Technique for Studio Portraiture

Direction of Light in Portrait Photography

By Neil van Niekerk 
The video doesn’t just focus on studio light, it also explains how to manipulate and use natural light to its full advantage by thinking the shot through. Since you can’t exactly move the direction of the sunlight, you can change the way it affects your photograph by repositioning your subjects so they are in a more flattering light.
Watch:

Fluid Mask 3 - Working with the Forced Edge Tool

Although I don't use this facility, I shared it here just in case you need it.

Colour Correct Skin Tone on Photoshop

Skin Tone correction has always been a challenge. One of the issue is the colour display we have which is not calibrated or whatever reason you may have. This tutorial by Lynda shows how to adjust the CMYK numbers to make color corrections to skin... enjoy!
http://www.youtube.com/watch?feature=player_embedded&v=eJiM-fsvQXE

As a general starting point, yellow would be a little bit higher than magenta, cyan is between 1/5 to 1/3 of magenta and yellow. For darker skin, the values would be higher.
Use info panel (F8) and click on the skin area to be analysed using the eyedropper tool (I) and check the values of CMYK. To change the value, use a curve adjustment layer.

Another video similar to the above: Whitening Skin for "High Key look"
Editing a Tan

Tips on Photoshop/Camera etc

Just some nice link/collection:

44 essential digital camera tips and tricks
225 tips from famous photographers

99 Common Photography problems (and how to solved them):

1. General Photography Problems
2. Using lenses
3. Digital camera accessories
4. Digital camera settings and controls
5. Camera exposure
6. Using flash
7. Photography technique

If you want to improve your photo composition, read this article:
10 rules of photo composition

Photoshop:
20 things you need to know about Photoshop CS6: Click Here
6 photo editing steps every photographer should know