I don't know what the "best" way is for installing a new video card as there is a gradient between work/effort involved versus confidence in the results.
The range can be as extreme as a complete system reinstall, plug in all hardware and do a fresh install of the OS plus all drivers - absolutely no question then as to the integrity of the installation of the new video card.
But that may be overly aggressive for some folks, including myself.
On the end of the spectrum you could attempt to get away with doing as little as plugging in the new v-card and rebooting the computer followed by updating the video driver with the auto-installer package provided by the GPU manufacturer.
That's probably the riskiest and most likely to cause driver conflict issues.
In between those two extremes you have options that include first uninstalling the video driver of your current card, then shutdown and swap v-cards, then reboot and install new v-card driver.
Another option, the one I personally choose to implement, is to just shut down the computer, swap hardware, then install new drivers while making sure I select the
clean install option (in Nvidia drivers at least, no idea about AMD drivers, I have AMD cards just have never updated the drivers (the horrors, I know

)).