Your user settings are in "%appdata%Poser Pro" or "%appdata%Poser"

Your activation key is in "%programdata%Poser Pro" or %programdata%Poser"

Other than that be sure to backup all of your runtimes. You can determine the path to each runtime by opening poser and right clicking an item in the runtime to backup. Then click [Show in Explorer]. That will drop you in the middle of the runtime. Just go up a few folder levels till you get the the parent folder of the actual "runtime" folder.

Or save the text below as a .py file and run the python in Poser. It will print out all the runtime paths. There's a version for P12 and P11.

Poser 12

import poser

print("Poser Program Location: ", poser.AppLocation())
print("Poser Flavor: ", poser.Flavor())
print("Poser Version: ", poser.AppVersion())
print("Primary Runtime Path: ", poser.ContentRootLocation())
print("External Runtime(s): ")
paths = poser.Libraries()
for path in paths:
    print("               ", path)

Poser 11

import poser

print "Poser Program Location: ", poser.AppLocation()
print "Poser Flavor: ", poser.Flavor()
print "Poser Version: ", poser.AppVersion()
print "Primary Runtime Path: ", poser.ContentRootLocation()
print "External Runtime(s): "
paths = poser.Libraries()
for path in paths:
    print "               ", path