How you invoke screen is a great start, But to go to an already active screen you could do..
screen -R -D
that will re-attach if there is already an open screen session. Also keep in mind if your running screen and just kill the window or the connection, screen will continue running. At the end of your screen session typing exit until the you get the " [screen is terminating]
" notice, will help keep screen from living past its needed time.
I would highly recommend reading the screen man page.