There is an advantage in arch (and all pacman based distros) that the pkg mgr is friendly and vocal.
Say you want your system to run with vtwm you try and you get many dependencies installed, then try starting it. If it doesn't start it will tell you what is missing still.
Usually with X is either xorg-xinit or a display manager (avoid) and adding exec vtwm into your ~/.xinitrc gets you going.