I think many folks already know this, but I'll try and put this in a simple way that I use to practice.
Basically, I will put in "box" positions - 4 different ones for playing major scales. Being box positions, u can move the box up and down the fretboard to play different scales.
Box 1 (also called 6-2, since it starts on the 6th string, finger 2). NOTE - this is NOT tablature, rather I show the fingers you use on the left hand
E A D G B E
| 1 1 1 | 1
2 2 | | 2 2
| | 3 3 | |
4 4 4 4 4 |
Just so that it doesn't cause confusion, you start with the 2nd finger on the 6th string, then 4th finger on the 6th string, 1st finger on the 5th string, 2nd finger on the 5th string and so on.
In the first position (note that in the first position, since u start with the 3nd finger, the very first note u'll play will be Gb), this is the Gb major scale.
Move it up one fret (or position) and u have the G major scale.
1st pos Gb major
2nd pos G major
7th pos C major
and so on.
So, u learn just one pattern of fingering and move it along and u can play all the major scales. Very useful when u want to improvise and solo or even change rhythm accompaniment - whenever u see a G major chord, instead of strumming the chord, play the notes of the G major scale (all of it, some of it, change the timing of each note, mix 'n match to make interesting accompaniments).
Would strongly recommend actually learning the underlying notes of the scale once u have the fingering pattern memorized - will help understand the fretboard immensely as well as understand the scales themselves. With the physical pattern under ur belt (or should I say under ur fingers !! Bad pun), u can start studying scales (its hard to concentrate on what u play and learn the scale at the same time - this hopefully takes one thing off the table and allows concentration on scale notes and fretboard positions).
Next time, I'll introduce the 5-4 box position. Till then, I hope this intro to major scales and position playing is useful.