Ok guy these are the most popular tunings for slide for blues playing.  I like Open E because I can get more bite from the tighter string tension.  But any way, heres my lesson.

Open E:  E B E G# B E
Open D:  D A D F A D

E
D (i chord position)
-----------------------------
-----------------------------
-----------------------------
-----------------------------
--0--0--2--2--0--0--2--2--
--0--0--0--0--0--0--0--0--


A
G (IV chord position)
-----------------------------
-----------------------------
-----------------------------
-----------------------------
--5--5--7--7--5--5--7--7--
--5--5--5--5--5--5--5--5--


B
A (V chord position)
-----------------------------
-----------------------------
-----------------------------
--2--2--4--4--2--2--4--4--
--0--0--0--0--0--0--0--0--
-----------------------------

Now all you have to do is play these chords in a 12-bar bluses progession and EUREKA!  Your the next Elmore James!!