Debian Unstable will provide you with newer packages, but there are inherent risks of breakages, since the packages have not been fully tested. If you do move to Unstable, it's probably best not to do it on a critical machine where you need guaranteed stability. With that said, the steps to move from Debian Stable to Unstable:

1. Using an editor such as nano, micro or vim open the Apt Sources file. Apt downloads packages from one or more software repositories (sources) and installs them onto your computer.

   sudo micro /etc/apt/sources.list
   

   

2. In the sources.list there needs to be only two entries (see screenshot below):

   deb http://deb.debian.org/debian/ unstable main non-free-firmware
   deb-src http://deb.debian.org/debian/ unstable main non-free-firmware
   

   The other entries/sources can be commented out using the # at the beginning of the line. This will stop them from running. You can also delete the unneeded sources if desired.

   

3. Next, to update the sources list run

   sudo apt update && sudo apt full-upgrade
   

   This may take some time.

Tip

In order to make your life easier in the Unstable version install the apt-listbugs and apt-listchanges packages so that you are notified "of grave bugs or important changes when you install new packages or during an upgrade." ¹

sudo apt update && sudo apt install apt-listbugs apt-listchanges

There is additional debian guidance for Unstable/Sid user which it is worth taking note of in the link below.

Sources:

1: Debian Best Practices for Sid/Unstable Users