thumb chords

nwilkins

you can often leave out the bass note, or pick a repeated note to omit:

Amaj6
x
7
6
7
7
x

x
7
6
x
7
5

ocicornija

I think key point in playing this chords is very strong bar with ring finger
which is used as pivot or guide finger .This finger is flattened.Also practice first with thumb on the sixth string ,first finger on the third string (form A6/9) and ring finger covering first two strings.Then add your middle finger on the fourth and fifth string.Never flatten this finger Just bend this finger in the first joint and cover by the side of your tip both string.This finger is approximattely 45 degres to the frets.Firs practice movements without midle finger and add him gradually.Later practice moving first finger half step lower to practice minor 6/9 form.When you move to other chord form relax your hand (grip) and slide your third figer.
If you develop strong bar with ring finger after that you can work on dexterity of index and midle finger just because you have strong pivot finger.In my opinion starting grip adjusting midle finger position before
you lay down you ring finger is the worst method and you will never be able to play this chor forms practicing that way.