I am using 2.5" strips of batik which doesn't have wide selvages so I can get 2 blocks out of every 2 strips sewn together. You need enough contrast between the 2 strips that you know which one is the light fabric and which is the dark fabric of the pair. Sew 2 strips, press the seam toward the dark fabric and then cut it into 2 equal pieces as shown.
Sew them together and press the seam toward the dark fabric.
Slice it into 2.5" segments. You should be able to get 8 (4 for each block) from batiks.
Flip strips 2 and 4 so colors alternate. Make sure that every block has the light fabric in the upper left corner (very important).
Sew seams to make a block and press seams all in the same direction.
The last seams sewn in the blocks should be in a vertical position all through the quilt top. Vertical seams on the top row go in one direction and row two in the opposite direction. The crosswise seams will alternate direction automatically because they are all pressed to the dark.
You will probably need to enlarge this last photo by clicking on it to clearly see that seams are going opposing directions at every intersection in both directions.