After spending lots of hours of smocking, you wear your fancy new smocked garment on a event, afterwards you throw it in the washing machine.
If you do not have a iron with steam, you take a piece of fabric, I use a linen kitchen towel and make it really wet in one end, Use a old washed fabric to prevent excess colour from staining your work. Squeeze out some of the water.
Then really lightly touch the towel with the iron just where your smock is. Do not apply any pressure, you only want the heat. The towel should now do a sizzling noise, the water turning into steam. If you happen to have a steam iron, you can just use a dry towel and then hold it over the towel and use lots of steam on the smock.
And this is how it turn out after cooling down, as good as new or perhaps even crisper. Now you can move on the the newt part of your garment and work your way around the whole smock, just to the same thing all over again.
And now you can go out, wear it at en event, throw it in the washing machine and then do it all again ;)