Hello, I have the Nikon D850 so I wanted to upgrad... (
Get a calibration kit from Datacolor or X-RITE. Follow the instructions to the letter.
Be sure you are making output files in the right color space! The usual reason JPEG images look great on a monitor capable of full Adobe RGB color space, and flat, lifeless, embalmed, and dead on other peoples' monitors, is that you set the color space for your output files to Adobe RGB instead of sRGB!
Adobe RGB is a good "working color space," but it is used by VERY FEW photographic labs. It is primarily used by (perhaps preferred by) the CMYK++ graphic arts world (lithographers). If you are in the real world, where over 90% of images are viewed on the Internet, your images should be JPEGs in sRGB color space.
Profile setup is very important. Having a custom ICC profile for your calibrated monitor is the starting point. Without that, I'd just give up! My Spyder5Pro is the best $150 I ever spent on any digital photography device.
Aim points for calibration are very important, too, if you print.
Black Point 0.5 cd/m^2
White Point 80 to 120 cd/m^2
Color temperature 6500°K
Gamma, if adjustable, 2.2
It is very important to turn down the brightness to the range mentioned (maximum 80 to 120 cd/m^2). Otherwise, prints and screen won't match.
Monitor location matters, too.
Gray surroundings are ideal. Eliminate brightly colored objects from peripheral vision.
Set your computer desktop to middle gray, or slightly darker.
Subdued, indirect, 5000°K lighting
NO glare off the screen, especially when calibrating.
Don't expect to adjust images accurately if you are upset, just came in from daylight, drank a lot of caffeinated beverages, use illegal drugs, or are pregnant. All of those things affect your color vision.
Allow monitors to warm up for an hour before calibration/profiling, and ten minutes or so before critical image adjustment.