If you are trying to use remote desktop on Ubuntu or Xubuntu 18.04 you may find that after logging in all you see is a blank screen.
One cause of this is that xfce4 has added code that prevents a second session from opening. You will find that if your computer's main screen is logged into xfce4 you may not be able to use it with xrdp.
To solve this "second session" problem and allow as many sessions as you need, edit /etc/xrdp/startwm.sh and add these lines before the lines that test and execute Xsession. The $HOME/.profile is not part of the solution, but is something that should be run before starting the session anyway.