Notes on Blocks Used
Dresses can be made using the Bodice and Skirt Blocks, or some kind of derivative Dress Block. On this website there are instructions for creating an Extended Line Dress Block.
If there is a waistline on the dress, then you would more likely use the Bodice and Skirt Blocks. Sometimes when making a dress with a waistline, you can use the Bodice Block, then create the skirt using the Bodice Waist as a guide (i.e. no need to use a Skirt Block).
If there is no waistline, you could use the ELD Block, assuming you have made one. Like all deritative blocks, it is better to do the work once when creating the block than have to create the dress outline each and every time you make a dress.
With common Stylelines such as Princess Line and Empire Line, these are marked on the block so they can be used again for future styles. (Even if you want to change the style, it is useful to have the previous lines for comparison, and will make creating the new style easier).