I’d be tasked with installing a GUI on a server for someone else to use. I opted for LXDE as it’s so lightweight and I just wanted the core, no extra gumph. I ran into an issue launching lxde once I’d installed it. Here’s how I fixed it:

Installed LXDE Core

sudo apt-get install lxde-core

I then went to try startx, how I’d normally start a shell if I’d installed gnome or such, startx didn’t exist, so I tired startlxde. It came back with the error “Gtk-WARNING **: cannot open display:”
After a bit of searching online I found some people were saying about .xinitrc, but I didn’t have an xinit…. neither did it seem that I had xinit. So I tried the following with instant success

The Fix

Install xinit

sudo apt-get install xinit

Start X

startx