Start off learning the notes along the low E string. When you know the notes on this string you will know the notes along the high E string because they are exactly the same. Then you can start learning the notes on the A string and the B string. I learnt in this order because the root notes of the major and minor chords are on the low E, A, B and high E strings.
The thing to remember is the notes on the next string down will be in the same order but just 5 frets different if you know what i mean.
Anyway. Its not as important to remember all the notes. Knowing the notes does help you find where a scale may start or where you should play a chord but once you have that its all about remembering the shaps and all the "gaps" between the notes.