Partitioning WD Blue SSD 500Gb in Linux

Hi, I am about to install a WD Blue 500Gb 3D nand drive in a new
linux server machine. I have read articles that advise that 20% of the drive should be left unused. I have also read that some drives have this free space built in. I plan to have a separate small /home partition and use the bulk of the drive for /var/www where I plan to install my apache webserver application. Can any one please advise on what the best partitioning strategy should be, Thanks