I agree Chaulkbuttes that a guitar player should learn all the notes on the fingerboard, but, as you know, for a beginner memorizing all them right away can be overwhelming and may even discourage them.
As a compromise, I would suggest the beginner initially concentrate on the natural notes for the E and A string to start with. This comes in very handy for determining the Major and minor roots to the scales they will use.
Also agree with Lyle on the patterns. Practice pattern one daily while learning other material such as various licks and songs. Move on to the next pattern only after the previous one can be played smoothly to a metronome while not looking at your guitar.
One of the road blocks I faced was that I would be attracted to the lead in songs that were way above my ability. I would try it and never finish it, which translates into knowing a lot of parts but not being able to play a complete song.
The way I got around that was to avoid the lead until I learned the Rhythm part and could play the rhythm part of a song completely through from start to finish. That part helped my confidence and has encouraged me to continue.
A real easy song to learn the Rhythm to is "Tease me, Please me" by the scorpions and its real fun to play as well as sounds cool...if you're into that kind of music.
A couple other ones that are easy to learn Rhythm to are Detroit Rock City and Love Gun and God of Thunder by KISS, and Rock you like a hurricane and No one like You by the Scorpions.