Open tunings allow the player who often plays alone have a full sound of rhythm and melody underneath his voice since there are no other players to fill these roles.

With an open tuning, you are usually tuning your guitar to a chord (alternate tunings are not tuned to a chord, but rather in a way to emphasize certain notes or drones).

Ppen D tuning is (from lowest to highest):

DADF#AD

So your strings become:

1st: E = D
2nd: B = A
3rd: G = F#
4th: D = D
5th: A = A
6th: E = D

To start, tune your 1st and 6th strings (high E and low E) down 1 whole step to D. Then tune your 5th string (B string) down 1 whole step to A. Last, tune your 3rd string (G string) down only a 1/2 step to F#.

Now, when you strum all 6 strings together, it should produce an open D major chord. If any strings are off (sharp or flat a little), now you can fine-tune them. This is the same as open E except the whole chord is down 1 step. Instead of tuning up to open E (which puts extra strain on the guitars neck), alot of players tune to open D and put a capo on the 2nd fret for open E tuning.

A common practice in open tuning blues is to still use the good ol\' 1-4-5 progression (or I-IV-V) while sliding at various times. This gives you the rhythm and lead in a song, and since alot of Delta-style players played alone, they did this out of necessity, to have a rhythm and lead going while singing (or rythym and melody).

The 1-4-5 progression (normally numbered in Roman numerals- I-IV-V) just refers to the chords played in a given key. So in the key of D, the I-IV-V chords are D, G, and A. In open D tuning, the chords for the I-IV-V are all now easily played by barring a whole fret with 1 finger.

The chords are:
D-G-A or I=D, IV=G, V=A OR 1=D, 4=G, 5=A

They are found on the following frets:
D= open strings, G = 5th fret, A=7th fret, D = again at the 12th fret

--0--------5-------7------12--
--0--------5-------7------12--
--0--------5-------7------12--
--0--------5-------7------12--
--0--------5-------7------12--
--0--------5-------7------12--

So to begin with (after learning where the 1-4-5 is at on the newly-tuned strings), you can start learning common blues-rhythm patterns while also incorporating some slide work. Everywhere you see a \"/\" means to use a slide and slide up or down to the notes /=up \\=down of coarse with slide playing you often use alot of vibrato with the slide. And remember that when using a slide, you slide directly over the fret, not in the middle of the frets where you normally fret notes at with your fingers!

Heres a short piece heavily influenced by \"Dust My Broom\" - a song covered by many including Elmore James with slide:

 use vibrato with slide often: (explained down at the bottom)

I (or 1)  D

|-/12-12-12-12-12-----------------------------------------------------|
|-/12-12-12-12-12-12-12-12-12--/15---15-------------------------------|
|-/12-12-12-12-12-12-12-12-12------15-----/12-------------------------|
|--0-------------------12-12-12----------------12---------------------|
|--0-----------------------------------------------2--2--0------2--2--|
|--0 ----------------------------------------------0-----0---0--0-----|


|-/12-12-12-12-12--------------------------------------------------12-12\\--|
|-/12-12-12-12-12-12-12-12-12--/15---15-------------------------------------|
|-/12-12-12-12-12-12-12-12-12------15-----/12----------------/12------------|
|--0-------------------12-12-12----------------12---------------------------|
|--0-----------------------------------------------2--2---0-----------------|
|--0 ----------------------------------------------0------0-----------------|

IV (or 4)  G

|----------------------------5-----------------------------5--|
|----------------------5h7--------------------------5h7-------|
|-------------------------------------------------------------|
|-------------------------------------------------------------|
|--5------7--7--5---------------5-----7--7--5-----------------|
|--5--5--5------5--5-----------5--5--5------5--5--------------|

Now back to the I (or 1 = D)  

|-/12-12-12-12-12----------------------------------------------------12--|
|-/12-12-12-12-12-12-12-12-12--/15---15----------------------------------|
|-/12-12-12-12-12-12-12-12-12------15-----/12-------------/12------------|
|--0-------------------12-12-12----------------------12------------------|
|--0---------------------------------------------------------------------|
|--0 --------------------------------------------------------------------|

V (or 5 = A)                    then the IV (4 =G)  
               
|-----------------------------7------------------------------5-------|
|-----------------------7h9---------------------------5h7------------|
|--------------------------------------------------------------------|
|-----------------------------------------------------------------0--|
|--7------9--9--7-----------------5-----7--7--5---------------0------|
|--7--7--7-----7---7-------------5--5--5------5--5-----------0-------|

now the ending in D (or \"turnaround)

|-----0---------0---------0---------------------------|
|----------------------------------------------0---0--|
|----------------------------------------------0---0--|
|----------------------------------------------0---0--|
|--3-----3--2------2--1-----1--0---------------0------|
|----------------------------------------2/4---0------|

OR this ending/turnaround:

|----------------------------------------------5/6/7-~~~~~~--|
|------3------------2-----------1--------------5/6/7-~~~~~~--|
|--3------3----2-------2----1-----1------------5/6/7-~~~~~~--|
|---------------------------------------0--------------------|
|---------------------------------------0--------------------|
|---------------------------------------0--------------------|

If you have never heard this song, it\'s great. and the flow is pretty easy (alot easier to understand if you\'ve heard it). The rhythm is a basic "boogie pattern" and is not fast or slow, just a nice flow.

When playing slide using \"vibrato\" always makes your slide playing come to life. Vibrato is noted by \"~~~~\" in alot of tablature, but you want some vibrato almost anywhere you slide:

|--/12-12-12-12-12--|
|--/12-12-12-12-12--|
|--/12-12-12-12-12--|
|--/12-12-12-12-12--|
|-------------------|
|-------------------|

Like that first part, dont just slide up to the 12th fret and stop, vibrato (or rapidly vibrate the slide) back and forth slightly over the 12th fret. To apply vibrato, slide up to a fret (any fret) and instead of just stopping and letting the note ring, slide back and forth (towards bridge and back to neck) however fast you feel. But try to keep the note right in the middle of the distance you are vibrating over, because vibrato too far in either direction will cause a sharp or flat note. you want the fret right in the \"middle\" of your vibrato.

And actually when playing a slide riff like that, it is common to keep sliding up every so often when hitting those notes, like this:

|--/12-12-12--/12-12-12--/12-12-12-----|
|--/12-12-12--/12-12-12--/12-12-12-----|
|--/12-12-12--/12-12-12--/12-12-12-----|
|--/12-12-12--/12-12-12--/12-12-12-----|
|--------------------------------------|
|--------------------------------------|

All the while, adding a fast vibrato!