Another trick for color grading that I like to do with my HERO6 and HERO7 Black, is I take a picture using default Protune Color - GoPro (Smart Photo on HERO7) and then switch to video mode and film with these settings:
Protune: ON
Shutter: Auto (sometimes I set this, but usually use Auto)
EV: -1 (-0.5 with overcast sky or 0 indoor or low light)
ISO MIN: 100 (except for indoor or low light which I use 400 or 800)
ISO MAX: 100 (if indoor or low light I match the MIN)
WB: Manually Set (for quick shooting I use Auto)
Sharpness: Medium (Low for indoor or low light)
Color: Flat
Manually Set shutter to the fastest possible when I'm going to do super slow motion.
Manually Set shutter to 2x (1/2xfps) for a better sensation of speed.
Manually Set shutter to 3x (1/3xfps) for better Hypersmooth stabilization in lower light (usually with 60fps, so shutter 1/240).
EV -1 or -0.5 to preserve the highlights. You can always bring up highlights and brightness in your editor, but blown out highlights captured with the camera cannot be saved. Better to fit a little darker and correct in post than too bright.
I try to keep ISO low to avoid noise/grain. In low light with Hypersmooth stabilization it seems to look best if both MIN and MAX have the same value. Sometimes I'll even go as high as ISO 1600 and correct noise/grain in After Effects.
WB set manually to avoid color shifts. Some people use NATIVE but I find this harder to color grade
Sharpness Medium so it's not overdone in the camera. For QuikStory videos, I use HIGH. In low light I use Low to reduce strength of noise/grain.
Color FLAT to preserve more detail in your shadows.
When editing in Premier, I load the picture at the front of my timeline and then add the corresponding video clip. I highlight the video clip and then go into the Color panel and select "Color Wheels and Match". Using the comparison view, I compare the picture to a similar spot on the video and then apply match.
