You will want to press your seams open. As you sew the triangles together, it helps to line them up.
I separated the triangles, each stack that I cut, went on it's own paper plate. I then played with the stack, getting the layout I liked best.
Then I sewed two together, another two together, then add on more to each pair. Keep these halves on the plate and go onto the next stack.
If you get these mixed up, it would take forever to get them all straightend out again LOL The paper plates stack nicely, and they easily go from the machine to the ironing board and then to the design wall :D:D:D