1. My recommendation for newbie is to go and download Live Image with different Desktops from Gnome to Cinnamon to Xfce to Mate and to a few more.
One can write this to a USB.
On a Linux Desktop it automatically goes to the Image Writer mode.
Alternatively, one can write this to a DVD. and boot it from an old PC that does not have USB booting.
2. Then there are Images for various platforms aMD and aRM, PPC and so on.
3. Then there are 20 odd DVDs.
They are source code and do not boot from USBs.
If you write the first DVD to a DVD, I think one can install.
I have not tried DVD method but I know it cannot be booted from a USB.
Connection to the Internet is vital.
Image in my USB was 6.2.0.18 (an old image).
On installation with WiFi connected it selected current 6.7.0....
The current Testing image is 6.7.0.....
Debian has 9 sub partitions.
I use that schedule but I have never tried on a single partition.
/root
/ boot
/home
/tmp
The above partition schedule with SWAP partition twice as the RAM is ideal or minimum schedule.
If dual booting backing up your data is an optional consideration (not for me) but mandatory for some.
Once installed one should run it several trial runs, so that Debian will automatically update its files.
Be patient when updating is going on.
Then one can install one's favorite applications either with SNAP store or Synaptic Package Manager.
I prefer Synaptic, it is really the Debian Package Manager.
Well I have 3 images installed in my NUC.
1. one for daily use.
2. One for testing.
3. The third is for the Testing Branch
Large DVD version has many types of desktops and one should not TRY KDE Plasma (files missing).
Installation hang up at the last moment when KDE is selected during (the Testing Branch DVD).
Go and s visit the Debian page for specific information.