don't keep any major files on your SSD... use the SSD for installing games and other commonly used application... download your drivers to the HDD but you will have no choice but to install them to your windows folder which is on the SSD... so...
-leave space for system-
not commonly used games or applications
files you don't intend to use on a daily basis
hope this helps
PS same thing with Windows updates... they automatically download/install where Windows is installed (which is on your SSD)... so for updates and drivers you don't have a choice but to install them on the SSD, it's a part of Windows...