It isn't that hard tbh...
The mistake most people make when trying to touchup is they SMOOTH the skin using the GAUSIAN BLUR
this removes all texture
What I do is:
Use a clone stamp and sample the skin VERY close to the spot and set my hardness from 0% - 75% (so it blends in)
this will remove the spot, but keep texture (the bumps)
(i resize my brush to the size of the spot each time though)
After i do that, If I am still not happy or there is too much tiny spots...
I duplicate the layer 2 times, Hide the top layer
then I Guassian blur the skin so it is porcelin soft. (like a doll)
and mask it so it only affects the skin and not eyes, hair etc..
then i show my top layer and set the opacity to about 10 - 30%
This adds the texture back in, but being subtle enough to hide the tiny imperfections
there is millions of ways to do it,
Ill try make a video tutorial (there are manyout there costing £100 - £800 just to show you, but ill give it out for free!!!! :O
But it isn't as good as the pros, The pros take anything from 3 - 6 hours to retouch, I usually wing it and take a maximum of 1hour to retouch a photo
(thus if you have seen my retouch in
http://www.thephotoforum.com/forum/...ork-you-beginners-welcomed-2.html#post1667160 that is why the halo is there, because I done that retouch in about 20 - 30 mins focusing mainly on removing spots, creases, re-constructing the mouth, enlarging the eyes, fixing the lighting (i dodged and burned some of the face and i Dodged the top lip (thats the bright pink line) to give a sense of depth.)
Ill try get a video up Asap, But currently i am fixing my laptop (I have formatted about 10 times in the last month... litterally... going from linuc, to xp to vista.. but xp n vista dont recognize my drivers whereas linux does but cant use photoshop, so i put vista in again and have finally got the drivers fixed!!! so i am installing all my apps again then creating a custom Vista Install disc so it installs all my programs for me if i need to format again...)
If you do not mind paying i Highly recommend this,
http://www.digitalphotoshopretouching.com/
I used that one, Learned quite allot.
But i knew the majority Prior to it, so was a waste of money in my point of view...
another good photoshop tutorial package you should look at:
http://www.photoshoptopsecret.com/
Worth the money IMO, It isnt what they are doing the effect to, It is how they do it you should study.
Learn the tools, Not the method.