Crease removal
If you have a subject where the head is turned, it’s inevitable that you’ll find some creases in the neck. The best method for removal is the Spot Healing or Healing Brush tools on a new layer, and set to Sample All Layers. Click bit by bit along the creases rather than trying to remove them in one sweep. If you get near to the edges of the neck, you’ll need to switch to the Clone Stamp tool to prevent the healing brushes dragging in areas outside the skin, which will give a discoloured area.
This same technique can be used to remove forehead wrinkles and wrinkles in the cheeks. Wrinkles around the eyes are best removed by moving in close with the Clone Stamp tool because of the proximity of the eye and lashes. To maintain some realism, you may want to drop the opacity of your new layer to prevent things looking too smooth.