*nodnod* As did I, the timing was pretty good.
Welp it depends what you are making really but the basic way to measure elastic is to measure what it goes around then remove an inch or so (how much depends on how big the measurement).
Eg. For a waistband I'll wrap the piece of elastic around my waist loosely then pull it in a couple of inches so it's slightly stretched out, just enough for it to be able to stay in place but not too tight (I'll also hold it together and make sure I can get it over the hips of doom before I cut). Then cut of the amount you need.
And for the basic technique to insert it into a waistband: You should sew the top of your garment up almost as if you were hemming it so you make a tube of sorts with an opening, the size the tube should be depends on the width of your elastic. Attach a saftey pin to one end of your elastic and pin the other end to the opening in your fabric (your elastic should be shorter than your fabric and you don't want to loose the end), thread the end with the safety pin through your tube until it comes back out the opening, unpin the other end and sew the elastic together then sew up the opening.
...If that didn't make any sense I shall try explaining at a decent hour, I promise it is actually really simple. sweatdrop
She has freakish hand sewing skills, I am in awe of them. I'm borrowing the pattern to make my own coat but I shall be using my machine. *clings to sewing machine*