guitars

Learn a lot of Bluegrass songs and you'll get a feel for what chords go together - Bluegrass does not tend to use a lot of Jazz chords, but you will need a capo.

Look at the white keys on a piano, starting at C (white key next to the two black keys rather than three). The intervals between those white keys are TTSTTTS (tones and semitones). If you play C-E-G, you get a Cmajor chord. Now, if you take those three fingers and work your way up the keys, always skipping one key, the chords you will get are C, Dm, Em, F, G, Am, Bdim, and back to C.

If you start at any note on the keyboard, and figure out the TTSTTTS pattern from there (G is an easy one, the notes of the G Diatonic Scale are G-A-B-C-D-E-F# and back to G - the farther away you get from C in the circle of fifths, the more Flats or Sharps (Accidentals) will be in the scale),

Anyways, you can follow that same pattern and you'll that same sequence of Maj-Min-Min-Maj-Maj-Min-Dim, which are called Diatonic Chords. Basically, all these chords fit together beautifully with each other, in various combinations, with the most common set being the I-IV-V, which in C corresponds to C, F and G - the roman numerals refer to the chord you find at a given step in the diatonic chord scale. So for the G scale, your chords would be G-Am-Bm-C-D-Em-F#dim.

But there are all kinds of ways to mess with that basic harmonious formula, that I will not get into here, but find yourself a good theory course and go all the way through it. But mostly, learn those Bluegrass classics, and realize just how many are mostly I-IV-Vs with some tricky little bits thrown in here and there - it's not Jazz and never tries to be, though there is virtuosity everywhere.

It's really not complicated: in the US, AC cords are either two or three wires, which you can tell by the number of prongs sticking out of the plug...

Sorry, couldn't resist teasing about the chord/cord mix-up. 😜

I read online that you can incorporate shifts like V-I at the end of a bar, and usage of I-vi and II-V are common in your genre. For C major, this means:

G-C C-Gm D-G

Source

And here is a simple guide on why the Roman numerals and what they mean. You have to apply the number in the sequence to the correct note and then correspond it to a chord. Lowercase for minor chords.

Good luck!

You might find Circle of Fourths or Circle of Fifths (they're really the same, just one has the fifths going clockwise and the other has the fourths going clockwise) helpful.

I found this general theory series really helpful. Doesn't matter that he uses piano, it's universal, just a bit easier to visual on a keyboard

https://youtube.com/playlist?list=PL1302D94F247600CD

if it better to follow c, d , e, e# etc… or c, g, a?

Think of music theory like learning a new language; there is no objectively "better" pattern of words to create a sentence. It depends what you want to say. Of course you need to learn basic rules to start, like IV>V>I or ii>V>I chord progressions, but that won't take you very far. After that there's a near infinite musical vocabulary you can use to make interesting music.

Primarily, keep listening to, learning, and analyzing music you love. That is the most natural and fun way learn, but it also requires a baseline of music theory. For that you may want to supplement with some academic reading such as these:

more guitar oriented:

https://www.amazon.com/GT15-Guitar-Grimoire-Progressions-Improvisation/dp/0825831970

more general which will require some musical notation reading:

https://www.amazon.com/Chord-Progressions-Theory-Practice-Everything/dp/0739070568

This may be great or terrible, I'll let others chime in.

I always understood theory as the fretboard being a matrix of "a.bc.d.ef.g." where the "." is disallowed by that key. If you learn modes and chords as shapes, you realize every key is just that matrix moved around a bit.

Where it messed me up is I don't think in numbered chords, I think of what the "c chord" looks like given the ionion is now centered on E string fifth fret.

The advantage is you'll know very naturally where all your major and minor thirds are, as well as weird stuff like diminished. If you ever do jazz, it'll be easier for you to flat something or add a 13th.

What I'd suggest to nail the "feel" of different chord progressions is just laying some runs over the progression. You'll figure out pretty quickly what number they're treating it as because if you're playing ionian when it should be mixolydian, the notes will be off. That implies your matrix is in the wrong spot and needs to be shifted.

Start by learning the C major scale and how you build chords from that scale. Its not that complicated, do not go into too much details for now, just learn the scale and their related chords. Also knowing basic intervals helps a lot in building chords. Have fun!