When you are done with the installation, make sure that Disk Defrag is disabled.
And if you do not use hibernation, you may also want to delete the hiberfile. The Command is : powercfg.exe -h off
It saves you a few GIGs on the SSD. All the other OS files should stay on the SSD.
If you want to move your user files to the HDD, here are a few tips on how to create a Data Partition