Expanding this, especially point 1, is the crux of the recent discussions. When I say "Learn the major scale and how it's constructed", I do NOT mean "be able to wiggle your fingers to the right spots to play a major scale". For this, "knowing" the major scale means:
A. You know its construction- W W H W W W H
B. You know how to determine the correct notes (with the correct enharmonics- it DOES matter) for the scale in any key. That is, you know how to figure out that A major is A B C# D E F# G# A, and you know WHY it's F# and not Gb.
C. You know what it sounds like.
D. You can find the notes for it and play it across the neck starting in any position (not necessarily starting on the root- this is vital for actually playing music instead of playing scales), and you can find the correct notes and figure out a fingering across at least two whole octaves to get from the first fret to the 12th.
Only then do you KNOW the scale. And the diatonic major scale is the first one to learn like this. In fact, you could a long way with that being the only one you know.
For point 2 (Learn how basic chords are built from the major scale- e.g Major is 1,3,5, minor is 1,b3, 5, etc.). This is covered in any basic harmony book. The goal is to be able to figure out for yourself (that is, no book or chart or diagram) the notes to the main types of chords. I think you should at least be able to spell out:
A. Triads- major, minor, diminished, augmented
B. 7th chords- Major 7, Dominant 7, Minor 7, Minor 7b5 (a/k/a "half-diminished"), and diminished.
In order to be able to do this for any chord, you need to know the correct notes in the major scale. So, instead of trying to memorize that an Abmin7 is Ab Cb Eb Gb, just build your knowledge- You know that the major scale is W W H W W W H. Start on Ab (the root) so the whole step is Bb, the next whole step is C (the third), half-step to Db, whole to Eb (the fifth), whole to F, whole to G (the 7). And from knowing that a minor 7 is 1, b3, 5, b7, you pull Ab, Cb (not B), Db, and Gb.
3. Learn the Harmonized scale- write out the scale on paper. Using C as the example, you'll get:
C D E F G A B C
On top of that write out the EXACT SAME scale starting on the third note:
E F G A B C D E
C D E F G A B C
Do it again a third higher to get the triads:
G A B C D E F G
E F G A B C D E
C D E F G A B C
And one more time to get the 7th chords"
B C D E F G A B
G A B C D E F G
E F G A B C D E
C D E F G A B C
Then ANALYZE those stacks so you see WHY the I and IV are major 7th, why the ii, iii, vi are minor 7th, why the V is a dominant 7, and the viii is a minor 7 b5. Instead of memorizing merely that they ARE those kinds of chord, learn WHY they are. It'll help a lot. And a lot of this is stuff you can do on the bus, during pointless meetings, and in your head when your wife is telling you about those new shoes....
Point 2 and 3 lead right into the other part of the original question in this thread. Now that you own the scale, and you know how to determine the correct notes for the primary chords, find 'em on the bass. Don't get a chord or arpeggio chart, figure them out for yourself and write your own chart. It will bring this stuff home to you in a way that merely looking it up won't.
Take the chord progression to a song you know, and write out the chords. Then figure out the arpeggio for each chord. Find the notes (again, don't limit it starting on the root) all over the neck. Then compare that to the bass line for the song. Yeah, there'll be notes that don't follow the arpeggio and sometimes not even the key. But look for where the chord notes ARE.
For example, check out what Jack Bruce plays for the Cream song "Badge". The chords after the bass intro are Amin to D to Emin (it's a chord that's essentially an E root and 5 with the high alternating between F# and G- it's an E minor tonality). For the Amin chord Jack simply plays A C and E; hammers the root for the D chord, then plays essentially an E minor scale under the Emin chord. "My Girl" has Jamerson playing just the root and fifth for the intro. "Ain't Too Proud To Beg" is 1 3 5 on the C chord, 1 and 3 for the F chord, etc . If you KNOW the arpeggios, you'll SEE 'em in the bass lines you know and you learn.
That's enough of the 8 points for now, but I want to leave you with this too.
SING everything you play. Playing music is about sound, not physical location. If you sing everything you practice (even if you sing like me- a friend described my vocal ability as "a duet with Yoko Ono and Linda McCartney") then every move your fingers make has a sound associated with it. So when you hear that Amin arpeggio in "Badge" your ear tells your fingers what it might be. So when you hear something similar in another song, you have a head start on finding it.
John