Learning notes on the fretboard always seemed impossible to me, until I tried this way.
We would start by learning all 7 natural notes. (Notes without #'s or b's)
We won't use any open strings, and will learn notes up to the 12th fret. Everything after the 12th fret is just a repeat.
The video below explains how to write down the locations on fret and string, and go from there.
Once you have completed the first note (E), I would learn the rest in this order:
G - B - F - D - A - C
Just to space things in a way so that you don't confuse them.
Pretty easy once you get started. Use as a 1 or 2 minute warm up everyday, longest it should take you is 1 week per note. End of 7 weeks, Presto! You know the names, which is important.
I tell my students, when a painter paints, he knows what the colors are he uses and it is just as important for us to know our note names :)