Drop the low E a whole step to D and you get a big low end and one-finger power chords on the bottom three strings. The catch: every chord that used the low E string moves.
Below are common chords in Drop D, each a full voicing with the root, third and fifth. Frets read low string to high; x is muted, 0 is open, and fr marks the starting fret.
x 3 2 0 1 00 0 0 2 3 22 2 2 1 0 03 3 3 2 1 15 2 0 0 0 3x 0 2 2 2 0x 1 3 3 3 1x 0 2 2 1 0x 2 4 4 3 20 0 0 2 3 12 2 2 0 0 04 4 4 2 2 2Ten seconds on why the shapes change: the Drop D Short.
Tune with a tuner that knows the target, not one that guesses the nearest standard note. Chartless has Drop D built in: pick it, strum, and each string shows how far it is from the Drop D pitch.
Chartless listens to whatever is playing and shows the chords live. Set the tuning to Drop D and every chord in the chart is shaped for it, so you can play songs you already know in the new tuning the same day. The live chart and tuner are free.
Other tunings: DADGAD · Open G · Open D · Double drop D · Drop C · Open E · Open C · Open A · Open D minor
More: chord finder · free online tuner · every tuning, with the notes · capo chart · Nashville numbers · why your guitar sounds out of tune.