Reducing imperfections in a subject's skin, ie, one aspect of "retouching a photo" is an art that demands years of experience to do well.
I'm not sure why one might think that adjusting the tonal curves should give you the desired smoothing effect. Photoshop tools like "curves", as well as "levels", "contrast / brightness", "vibrance", "hue / saturation", and all the others found in the "adjustment layer" menu only derive the new value of the pixel from the old value of the same pixel, with no regard whatsoever to the RGB value of neighboring pixels. On the other hand, all the blurring, healing, cloning, patching, high pass filtering, and related tools determine the new value of each pixel by considering the values of other pixels in the image. This is what is needed is needed to "fix" skin, and you will likely see skin "smoothing" tutorials based on each of the tools I just mentioned.
Probably the most frequently suggested automated approach is to make a copy of the image, blur it, and then add in a part of the blurred version to the original using various blending modes as well as the opacity and Blend_IF sliders. Unfortunately, while simple, this approach is one of the worst because to get enough of a smoothing effect, one almost always makes the skin look like plastic.
At the other end of the spectrum of automated approaches are the "frequency separation" methods. The theory behind these is complicated, but the results are well worth it. To read more about this family of methods, Google {chrisdesign frequency separation site
hotoshopgurus.com}, but I suggest you not start with these unless you are already quite familiar with PS.
Professional, high-end retouchers almost always use a combination of methods -- manual removal of major skin problems followed by an automatic method like frequency separation to give the pores just the right level of visibility.
I'm sure other folks will chime in with their thoughts on the subject.
The best of luck,
Tom M