I found this method on the web, so it isn't my own method, but I find it to be the easiest I have come across. Craftybear asked me to post this.
Open the blocks up, press well. With the 1" 'tags', fold the edge of the backing to the edge of the block, then fold over again on to the block itself. Top stitch down each respective side. I used matching threads for all of my block tops and backing. With this method, I was able to create another block design with the backing. The blue was on the corners, I did white diamond shape then in the middle a different fabric. I did one row at a time, then attached the rows the same way. This will also give you a sashing in between each block. Binding done in your own method.
The backing is 15" square, the batting is 13" square and the block itself is 12-1/2" square. Backing is right side down, batting block right side up. I stippled the blocks used in this tutorial. You could SID if you wish.
Here I tuck back the backing, as not to cut it (I did this once) as I trim the batting to match the block size.
Now I trim the backing to 1" width. Be careful not to cut the backing to the block top. ( I did this once as well!) The top and the batting should be 12-1/2" square, and the backing 1" larger all around.
Since the blocks are same size, put the blocks with backings right sides together and sew right along the top block edge. This will give you 1" from the block edge to the backing edge. The blocks will meet together very nicely.