Several people have asked me about sewing with elastic thread , or shirring. There are several patterns out on the market today which uses this technique. Shirring is fun and is quicker than running multiple rows of cased elastic to get the same effect.
Seeing is believing! Close up pictures should take away any fear of working with elastic thread.
Seriously fellow sewers, this is EASY. The elastic thread ...is...uh elastic. It does all the work. You sew and let the thread take care of the rest. :-)
My trusty old Bernina 930 is still alive and kickin! This is the stitch setting I use. I think it is actually called a elastic stitch. I find the stitch width works well between 3.5 and 4 and the length at about 3.5 - 4. Your machine may be different with those settings. Practice on a scrap to see how your settings compare with my sample pictures.
I've sewn samples using a plain straight stitch as well as a plain zig zag. Both work.....because the elastic thread does the real work. 
The first row is rather unimpressive. It doesn't start looking drawn up enough until another row is added. The closer you sew the rows, the tighter it draws. Keep that in mind.
The Pink Fig patterns , such as the
Cuppy Cake dress and
Lily tops, say to sew approx 1/4 -1/2 inch from the first row.

Things start to look good with each additional row.

This is the same sample piece. I stretched it for you to see what the right side looks like. Remember, the top thread is regular sewing thread.

Wrong side of fabric. Stretched to show how the elastic thread looks.

In this sample I used a regular Straight stitch.

Here is the standard zigzag.
Both the straight and standard zig zag seem to pull up tighter. You may want to space the rows out a tiny bit wider if you use these. Chances are, you are sewing on one of those fancy-spancy machines which tells you exactly how to set it up.
Leave yourself about of inch of thread tail to tie off each row. I still back stitch at each end, but I may be breaking the rules by back stitching. Instructions say to tie off.
Once you have sewn all of the shirring rows, make sure you have tied off securely. Take your piece to the steam iron and blast it with some steam. The elastic goes back into shape and looks wonderful.
Step back, and take pride in your handy work!