Please view it on pixiv
Consider this a lesson in color adjustment.
1) My painting imported from PaintTool SAI,
2) Added a couple gradients on multiply and then a medium-dark layer on overlay to heighten contrast and increase saturation.
3) Took it into adjustments > Color Balance; shadows added a smidge of blue and magenta, middles a touch of red, highlights both red and yellow. Also checked the levels and got rid of the blank space on either side (I always work too much in the middle, not enough darks or lights)
4) Final version, desaturated it a bit since it was too intense before.