Update
The first thing to do after installing Ubuntu (even if you choose to install updates during install) is to run Software Updater.
Remove Unused Software
This is optional. I am careful about doing this most of the time as it has ended in accidentally removing files that other applications require even though that is not supposed to happen. While there is a minimal install option for Ubuntu 18.04, I wish the user had more control over what is and is not installed during a clean install.
Install Any Software You Need
This can be tricky. Some software is available only as downloadable .deb packages, some has to be installed from the terminal, some requires adding a repository manually in the terminal, etc. The Google is your friend.
Remove Example Content sudo apt-get remove example-content
This content is utterly useless, and the folder in the home directory is annoying. I have used this command with no ill effects since 17.10. After running the command simply delete the Examples folder from your home directory.
Remove Amazon Web Launcher
Also utterly useless. I have used this command with no ill effects since 17.10. sudo apt purge ubuntu-web-launchers
Install GNOME Tweaks sudo apt-get install gnome-tweak-tool
How you setup your environment is personal preference, but GNOME Tweaks adds a few more options. I turn off desktop icons because I want it clean. I also turn off animations to make my system a little more responsive. I personally prefer not to have modal dialogs attached to their parent windows so I turn that off as well.
Customize GNOME Terminal
This is all personal preference. I like to have some transparency to the terminal window so I can see commands from the Interwebs and type them without going back and forth or copying and pasting. In addition, you can customize the prompt and window title.
