I tried out this coast line technique on the below map and struggled on the north and south coasts because it is fairly flat. Beyond not shaping future continents like a rectangle how could I have done this better, or should I have just picked a different coast line technique that better suited my shape?

This was my first ever map so maybe it was just poor for thought on my part

Click image for larger version. 

Name:	001-29-03-20Final.jpg 
Views:	63 
Size:	888.0 KB 
ID:	121238