When sewing anything where four points join together, such as four squares, first sew them together in pairs of two.
Press the seams of each section so that, when right sides are placed facing each other, the seams will go in the opposite direction and will nest together.
Place the two sets of squares next to each other with right sides facing and one seam going one direction and the other in the opposite direction. This creates a ridge where the two seams can butt next to each other ,helping to keep them in place. Put a pin directly through this ridge and begin sewing from one side.
As you approach the center, carefully pull the pin out and make sure that the two seams are still butted next to each other. Now (if you are right handed), gently pull all the seam allowances to the left and sew right up to the seam line. Make a tight back-stitch.
Next, gently pull the seam allowance to the right, take another back-stitch right next to the seam and continue sewing across the seam.
The secret of getting points to match when hand piecing is to take these tight back-stitches where seams meet, and to never sew the seam allowances down, always leaving them free.