Here's the back of the block. As you can see on the innermost seam, I didn't press all of my seams toward the edges. The top one is and the bottom one isn't. It's much easier to get sharp points if you have that "x" seam visible to sew through. I did press all the next seams outward.
Notice that with the seam closest to the edge that the middle part wants to go outward and the ends want to go inward. I fixed this by clipping the seam near the ends of the rectangle. If you do clip seams, be sure not to clip all the way to the stitching. This will weaken your seam. It is also fine if your seam is pressed in two different directions without any clipping.
It is also okay to press seams open. The tradition of pressing seams to one side got started when blocks were hand-pieced and carried over to machine pieced blocks.
You might also have noticed I didn't piece this block exactly as my instructions are written. That's because I accidently sewed a side unit to the top and didn't want to rip it out.
Click here to see the front of the block.