Start with one possition only (you deside which fits you the best) and then practice descend and ascend, from all keys! Then, as you may have read here on guitartricks.com, there are relatives to the major scale.
There are 7 notes in the major scale. The first note is the root, ex. you play a C-major scale, the C-note is the root.
Second note is the D. If you now play exactly the same scale, but start on the D and work your way up to the octave, you've just played the D-dorian scale/mode.
So now you just play the same scale all over, just changing the root-note and applying the octaves above.
The modes of C-major is: (in brakets, the overall tonality)
Root = C-Ionian (major)
second = D-dorian (minor)
third = E-phrygian (minor)
fourth = F-lydian (major)
fifth = G-mixolydian (major)
sixth = A-aolian (minor)
seventh = B-locrian (minor, not really a cool scale for much other than jazz progressions)
That's it! All this is writen in thousands of books and you can find the scales here on the site and start from there.
Don't forget other possitions, all keys and most important: memorise the sound of the scales and try at all time to train your ear, ex. move the scales around by yourself rather than take a peek in a book.
Good luck!
Fiddles
Trolle
