One of the things I like better about Mint is the Nemo file manager, which is streets ahead of the default Gnome file manager, the imaginatively named "Files".
Googling for "install nemo ubuntu" or similar returns a bunch of people suggesting you install the "noobslab" repository like this:
sudo add-apt-repository ppa:noobslab/nemo
You can do that if you want to, but if you prefer to minimise the number of third party repositories on your system you can simply enable the ubuntu-backports repo in your sources list instead.
Whichever way you choose, simply install Nemo like this:
sudo apt-get install nemo
Now that Nemo is intalled, we should make it the default file manager too. Enter this into the terminal console:
xdg-mime default nemo.desktop inode/directory application/x-gnome-saved-search
And that's all folks.