I would concentrate on the base texture initially - try desaturating the colour of an existing texture (use a copy!) to get the base colour paler. Once you are happy with that then start to add detail a bit at a time on a seperate layer and do regular tests of the merged layers to see if you are heading in the right direction. A bit of darkening in the natural folds of the skin wont go amiss - ie: forhead, side of nose, laughter lines. With patience and persaverence you will get there. Following your own ideas instead of tutorials may be the biggest help.