One of the tricks is to make 1/4 of the Dresden plate and square up the edges. Do this with all 4 quarters and then sew them together. Two 1/4 of the Dreden plate to another 1/4 Dresden plate and then straighten the edges with a ruler. Now lay the 1/2s on top of each other and sew. Press all seams to one side around.
this is pretty similar it only doesn't show trimming at 1/4 and 1/2 Dresden Plate.
http://www.sewmamasew.com/2010/04/dr...ock-sew-along/