Drop D tuning can be tuned by doing the following.
Drop D tuning is the same as standard notation except that the 6th string is lowered a full step. Because of this, all of the notes are the same except that the 6th string has the same notes as the 4th string, but the 6th string's notes are an octave lower. Many rock musicians like to use this tuning. Some guitars, like Eddie Van Halen's guitar, are equipped with a drop D switch. This switch basically lowers the 6th string to a D (therefore making a drop D tuning) when you use it. Chords for this tuning can be derived from the chords you know in standard tuning. You can do this by moving whatever note is on the 6th string of the chord up 2 frets (a whole step).
Drop D Fretboard
Half step down
Tuning to 1/2 step down can be done by lowering all of the strings by a half step. Follow these instructions to tune to this.
This tuning is widely used. all of the chords in this tuning can be played by simply using the same patterns as in standard tuning but sliding them up one fret. Several musicians like Stevie Ray Vaughan and Jimi Hendrix use this tuning to get a lower sound. It also takes some tension off of the strings so they are easier to bend. You can derive chords in this tuning by sliding the ones that you know in standard notation up 1 fret (half step).
Half Step Down Fretboard