I did that, and it took about 5 mins ;-)
As has been said above, there's a lot of tutorials around, and it's a case of finding what suits you. The process for the above was fairly short, and would probably be described as my typical workflow, although for the purposes of this shot, I took it to extremes.
1. Healing tool on any large blemishes - Not many on this image, don't go mad at this point.
2. Skin Smoothing - I use an action / plugin for this, then mask, merge, blend accordingly.
3. Skin Lightening - actually part of the above process, but worth a separate mention.
4. Revisit the healing tool
5. Then break out liquify......(only one touch with liquify on the above image, can you guess where???)
That's all I did on the image, and I honestly spent no more than 5-10mins on it. Dee's got a good base to work from
For me, I want the skin to retain its natural texture, and not look too "synthetic", ending up looking like it's been achieved with makeup, as described above.
Some methods will lose the skin texture ( pores, tiny creases etc) so bear this in mind when trying them out.
Once you get the hang of it, it can be done quite quickly, you just have to know when to stop!!!
Tools & Stuff
The commercial action I'd recommend looking at (at least to begin with) is from Mama Shan and called Powder, it's $25 ( so about £15) and a great place to start, because it saves faffing about with gaussian /surface blur high pass etc.
http://www.photoshopmama.net/index.html?reload
Demo video / tutorial
http://www.youtube.com/watch?v=w3OS46DfykA
I started with Powder, but have progressed to another plugin, and still use it occasionally, I tried doing things manually but never got consistent results (and it took ages!!!!)
This is supposed to be quite good (for free) but I've never tried it
http://www.adobe.com/cfusion/exchang...&extid=1044841
Try a few actions & plugins, and find which one suits you best, as there are several different methods to achieve similar results. Although I do have an aversion to "Portrait Professional". It mucks about with bone structure etc too much, and is not my cup of tea.
And finally....
This is one of many ways to achieve the results "manually"
http://www.photoshopsupport.com/phot...-tips-cs4.html
Oh, proper final bit, well for now...
There are several good retouching forums out there as friendly as this one.