Sorry no pics, I used to many, Ignore the 50k warning

Well, what's isometric mean? OK, Isometrics are pretty much looking at something from the sun's point of view.
It is very popular in 2D RPGs [Not to be mistaken with topdown(oxymoron) view]

Here we will start with a two pixel, straight, horizontal line
http://i197.photobucket.com/albums/aa206/c...isotutorial.png

Now repeat that line
http://i197.photobucket.com/albums/aa206/c...sotutorial2.png

Now do that over again until you have a big line
http://i197.photobucket.com/albums/aa206/c...sotutorial3.png

This part is VERY important, get your selection tool and turn transparency ON
http://i197.photobucket.com/albums/aa206/c...sotutorial4.png

select your line
http://i197.photobucket.com/albums/aa206/c...sotutorial5.png

copy (CTRL and C) and paste (CTRL and V)
http://i197.photobucket.com/albums/aa206/c...sotutorial6.png

Go to image -> flip/rotate and then "rotate horizontally"
http://i197.photobucket.com/albums/aa206/c...sotutorial7.png

Connect the two, now select the enter "upside down V" and redo the last step except this time, flip vertically.
Connect the two to make a diamond
http://i197.photobucket.com/albums/aa206/c...otutorial10.png

Now copy the diamond, don't paste it yet though.
Draw straight lines coming from the edges of the diamond
http://i197.photobucket.com/albums/aa206/c...otutorial11.png

copy the diamond and put it on top of the lines
http://i197.photobucket.com/albums/aa206/c...otutorial12.png

Delete any extra lines
http://i197.photobucket.com/albums/aa206/c...otutorial13.png

find a base color and color in the box
http://i197.photobucket.com/albums/aa206/c...otutorial14.png

color the top in with a mid-tone color, the left side in with a darker color
http://i197.photobucket.com/albums/aa206/c...otutorial15.png

(OPTIONAL)
Color in the middle lines with a slightly darker color than the surface it is touching
http://i197.photobucket.com/albums/aa206/c...otutorial16.png

And here is the finished product