Open D tuning
The open D tuning is especially popular among guitar players who uses a slide. (Open D Tuning is not to be confused with Drop D tuning.)
When you retune your guitar, it’s important that you turn the tuning pegs in a direction that decrease the string tension and not the opposite.
To get the open D tuning on your guitar you tune it like this: D A D F# A D.
Blues chords "starter set"
D7: you can choose to also play on the 5th and the 6th string. You can also play with the 1st string open.
G7: an alternative is to include the 6th string and in that case mute the 5th.
A7: the 6th string can be played.
These are some of the chords you could play in open position when using this particular tuning.
Movable one finger (or slide) shapes
All you have to do is to lay your fingers over the four highest strings. You can also play on all six strings in some cases, which would result in a D as bass tone. As the pictures illustrate, the D chord can be played with all open strings.
The shapes are movable, so if you move the fingers two steps up the fretboard from G major you will get an A major.
All common major chords in open D:
C: XX 10 10 10 10
Movable slash chords, some examples:
In the style of Keith Richard
Keith Richard uses open tunings including Open D. If you're interested in typical chords, here are some (all used in "Street Fighting Man"):
C: 10 10 10 10 10 10
F/C: 10 12 10 11 12 10