(thank you very much ~Ash-Kamiya
for translating it!)
Finished picture + photoshop edit:
Other pictures where I used this method:
Please ignore the stupid chair =v=, it's so out of proportion and perspective~~~
I did this on a rush, sorry T_TA few notes about this guide:
Brush settings are really
important! Play around with the 'Color blending, opacity mix and persistence' options, you'll get different effects each time~ (I'd love to explain more about these options but my English sucks
Just try different settings and you'll see by yourself). Also, it's not the same if you use different colors on the same layer or in separate layers. For better blending results, use one layer for all.
I always set the min. size of the brush to 0% (airbrush to 100%)
I forgot to mention that the highlights layer is on Addition mode
Using different colors from the picture on the shadows / highlights will make your colors feel more 'integrated'. Also, try not to use always the same shadow tone or light tone, and play with the hue and saturation of your colors before selecting them.
I hope this can be useful at least for someone! if you have any questions let me know~!