Learn to dodge and burn. There are many ways to do this, the 3 most common are:
- Dodge and Burn Tool
- Brush set to Lighten or Darken
- Curves Adjustment Masked In
Dodge and Burn Tool
Create a new layer with 50% gray set to Soft Light. Some people even create two of these layers. Name it/them Dodge and Burn.
Then use the Dodge and Burn tool to fix the wrinkles and then the layer Opacity for fine tuning. For wrinkle reduction you really only need Dodge. I set the Range to Midtones, Exposure to 10, Protect Tones activated and then in a few seconds brought it to this:
Create a layer the same was as above in the Dodge/Burn method. 50% gray, soft light. Then select a White Brush and change the Brush Blend mode to Lighten. Lower the Flow or Opacity down to like 10% and have at it:
Create a Curves Adjustment layer and increase the midtones a little and if you want you can increase the shadows a tad too. A benefit of this method is the Curves will be adjustable so you can always change this later too (If you were needing to Burn then you'd do a second Curves Adjustment for Burning)
Then invert the mask and paint in where you want the adjustment to show:
This was quick but here's a quick gif showing before and after.