In this video Peter has replaced the original HDD Sony hard drive with a Samsung SSD. The video shows this trick step-by-step.
First you have to remove the front plastic cover and then you can access to the Sony branded screw.
Screw it up and you got the access to the original drive. You can replace it now with the new SSD.
You will be able to measure the speed change between the original and the new drive. Because of the new SSD is much faster than the HDD you are going to see a better loading time for almost all the games and a quicker access to nearly everything.
You can also update you Playstation 4 firmware from Sony’s Playstation website. The current latest version is 1.5, but updates are coming nowadays very often for the console. You have to put it on a USB stick and after you hit the power button for about 7 secs you got the chance to update your system. The update takes about 5 or 6 minutes.