Photoshop Post Processing
There are times when the subject of a photo could look a bit better if the lips color were a bit different (perhaps matching the background color or the makeup). There are, of course, many different ways to do this in Photoshop. You can select the lips and change the HSL values or make a very precise selection, copy, paste and then do the color editing. Or you can use this simple, quick, and easy method to apply any lip color and change it as many times as you want without having to edit the image everytime you want to try a new color.
Open your image in Photoshop.
Select the Lasso Tool (L) and make a quick selection around the lips of your subject (does not need to be precise).
With the selection active, go to Layer > New Fill Layer > Solid Color. Name this layer as "Lips" and click OK.
In the Color Picker window, pick any color you want and click OK. In this case, I will select the traditional red color #FF0000, but we will be able to change it later so pick any color you want.
With the "Lips" layer selected, go to Layer > Smart Objects > Convert to Smart Object.
Go to Filter > Blur > Gaussian Blur. Set the Blur Radius to an amount where you can see a good part of the lips covered, but with the edges barely visible and click OK. In this case, a Radius of 28 px seems to work just fine.
With the "Lips" layer selected, go to Layer > Layer Style > Blending Options.
Set the Blend Mode to "Multiply.
Hold the "Alt" key on you keyboard and slowly drag the white anchor point of the "Underlying Layer" slider about halfway and click OK. This will split the slider in 2 making the effect a bit more soft.
Go to Layer > New Fill Layer > Solid Color. Name this layer as "Lips Color", be sure to check the "Use Previous Layer to Create Clipping Mask" option and click OK.
Lastly, in the Color Picker window, pick any color you want to use for your lips and click OK. In this case, I will set mine to #E55DEE.
If you want to change the lips color, simply double click on the "Lips Color" layer thumbnail, pick any color you like and click ok.
And if you think you need some minor adjustments on the lips contour, you can edit the Lips Smart Object or simply apply a layer mask and hide the parts that you do not want colored.