You picture is slightly bluish; white balance seems off.
If you want to control white balance before the image is captured,
you need to read up on white balance and/or use test/reference
shots with something like ExpoDisc or WhiBal products.
If you want to adjust in post-processing.... I got better skin tone
on your JPG by using a point-and-click white balance tool in an
editing program to click on the bark-less patch on the tree, which
I'll presume should be truly neutral gray.
The white balance tool will remove color casts from things in the
image that
you decide should be neutral in color
(white/gray/black). Automated white balance tools in-camera or in
post-processing are not perfect and can make mistakes in assuming
what should be neutral.
If white balance adjustment does not help (at all or as much as you
like), check your monitor calibration.
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