1) There are three (3) chord SHAPES to be memorized: E-shape, A-shape and C-shape.

2) There are three (3) chord DEGREES to be memorized: ROOT (R), THIRD (3) and FIFTH 
(5).

3) Each chord DEGREE has three upper and lower extensions; you count up or down from
the DEGREE note (all within 3 frets above or below).

4) A dominant-seventh (d7) note accompanies "extended" chords (9, 11 and 13); 
ie: 9 = 2 + d7; 11 = 4 + d7; 13 = 6 + d7.

5) Use four (4) note chords, unless using 'gran barre.' 

E-shape (key of A)

e|----R---
b|----5---
G|-----3--
D|------R-
A|------5-
E|----R--- (root in bass; root on E6 string)

A-shape (key of D)

e|----5---
b|------3-
G|------R-
D|------5-
A|----R--- (root on A5 string
E|----5--- (5th in bass)

C-shape (key of E)

e|---3---
b|----R--
G|---5---
D|-----3-
A|------R (root on A5 string
E|------5 (5th in bass)

HINT: can you recognize the 'repeating' R,5,R,3,5 sequence?

I.  ROOT (R)
----------------------------------
The extensions ABOVE any ROOT are:
 b9  = 0.5-step above ROOT.
  9  = 1.0-step above ROOT.
 #9  = 1.5-step above ROOT (Note: sharp-nine(#9) same as flat-third(b3) or minor).

The extensions BELOW any ROOT are:
 M7  = 0.5-step below ROOT.
 d7  = 1.0-step below ROOT.
  6  = 1.5-step below ROOT.

III.  THIRD (3)
---------------------------------
The extensions ABOVE any THIRD are:
  4  = 0.5-step above THIRD.
 b5  = 1.0-step above THIRD.
  5  = 1.5-step above THIRD.

The extensions BELOW any THIRD are:
  m  = 0.5-step below THIRD (Note: sharp-nine(#9) same as flat-third(b3); minor).
  9  = 1.0-step below THIRD.
 b9  = 1.5-step below THIRD.

V.  FIFTH (5)
---------------------------------
The extensions ABOVE any FIFTH are:
 #5  = 0.5-step above FIFTH.
  6  = 1.0-step above FIFTH.
 d7  = 1.5-step above FIFTH.

The extensions BELOW any FIFTH are:
 b5  = 0.5-step below FIFTH.
  4  = 1.0-step below FIFTH.
  3  = 1.5-step below FIFTH.

Example #1. Create an Aaug7 (A7#5,A7+5) chord:

e|----R----
b|----.5--- (raise 5 to #5)
G|-----3---
D|----7-.-- (lower R to 7)
A|------.-- (not played)
E|----.---- (not played)

NOTE: (.) represents original note/position


Example #2. Create an A minor-eleventh (Am11) chord:

e|----.----
b|--4-.---- (lower 5 to 4)
G|----3.--- (lower 3 to b3/minor)
D|----7-.-- (lower R to 7)
A|------.-- (not played)
E|----R----


Example #3. Create an A minor-Major-sixth (AmM6) chord:

e|----R----
b|----.-6-- (raise 5 to 6)
G|----3.--- (lower 3 to b3/minor)
D|-----M.-- (lower R to M7)
A|------5-- 
E|----R----

NOTE: this is a 'gran barre' chord, the index finger "bars" across all the strings
at fret 5.