Ugh right? Another one of these threads. I'm sorry but I do just have a few questions that I can't wrap my head around I've been reading a whole lot on theory in many different ways and a lot right here on MT. I've been playing guitar for a pretty good amount of time but just finally got interested in the theory part of it. I've also been playing a lot more lead lately and just finally got the major scale down.

I've been having a great time improving and although it's heaps and bounds over what I was doing just a month ago, I'm not quite satisfied with how it's sounding most of the time. What I do is take a song, or maybe a backing trace, figure out what key it is, and play the corresponding scale. I pluck around all over the different positions, and focus a lot on phrasing. Still I feel I'm missing something. I've noticed some people talk about playing over the chord progressions. So say in a progression of G D A, you would play the scale over the G, then the D then the A. What's going on here? I never focus on what chord is being played. Is this important? (I know, yes) and how does it work?

Another question I have is that I read somewhere that each major scale ascending is a different minor scale descending. I believe I saw that C major asc is A minor des. Is this true? If so, would playing a C major scale over a song in the key of A minor be acceptable? Why bother with the minor scale then? Just to mix it up a bit I assume?

Any other advice for improving would be appreciated, I just love it and can't wait to improve more and more
songs have key signatures .. k.. major and minor keys. say a song is in the key of G major.. you would for a start.. play G major scale.. or say a song is in A minor, play A minor scale.
G D A it matters what kinds of chords your playing.... and C major is that same scale patterns as A minor just a different root
Over your little D, G, A progression, just play in the key of D Major, since all those chords are in that key.
You could run through the scales for each chord, but you'll just be playing in D Major with a couple of accidentals technically anyway, depends on what you're after, try both.

C Major ascending is not A Minor descending..

The intervals are what gives each scale it's feel, for example..

C Major

C - D - E - F - G - A - B - C

These intervals are root, whole, whole, half, whole, whole, whole, half (root note).

A Minor

A - B - C - D - E - F - G - A

These intervals are root, whole, half, whole, whole, half, whole, whole, whole (root note).

These intervals/gaps between the notes are what makes it what it is, so even though C Major and A Minor have the same notes, they aren't the same thing.

When you have a progression in C Major, you can play the A Minor "shape" if you want, since the notes in it are all in C Major, but you won't actually be playing in A Minor, you'll be playing in C Major.

Learn some major scale riffs and licks for a few different major scale positions, and learn some minor and major pentatonic riffs and licks, and some minor scale riffs and licks, and you'll start to progress with your playing.
What you're talking about is soloing over chords, following them. This is good and helpful over much more complex pieces but in a simple diatonic piece won't make you sound like a good.

Say you've got your progression:

D G A D (rinse wash repeat)

The D chord has the following notes: D F# A C#

The G chord has: G B D F#

The A chord has: A C# E G

Right, now I'll explain that a bit. Those are the quatriad chords of your progression. That meaning, they have root, third, fifth, seventh as opposed to just root, third and fifth. I'm giving you the seventh chords because when soloing focusing on playing over chords, using chord tones it's important to keep the seventh in mind. Why? Because your third and your seventh are your guide tones. They're the most important tones in a chord. The seventh and third define whether the chord is major, minor or dominant. (won't go into other chords for now). So it's important when you're playing over the progression to land on those notes over the right chords.

At first that's going to seem hard, the chords are going fly by you and you're not going to be able to do it, but I'll give you a tip. Don't play 50 notes. Just play one. But make sure it's the right one. When you're confident about that start to make up some lines with them etc etc.

And if all fails rawk out the D major pentatonic!