It's interesting to see all the hints from so many people ... what really amazes me is that there didn't seem to be any disaster stories!
A tip that I will add is about the ironing ... both linen and cotton can tolerate a high heat. Like most of the posts, I roll the washed item in a towel to get out most of the moisture and then while is it damp, I iron it on the wrong side, face down on several layers of terry towel. As I iron, I flip the toweling so I have a dry surface until I have ironed the piece dry.
My stitches are plump, not flattened at all because of the softness of the towels. My linen is crisp and looks fab.
I'm not a slob but I do want to enjoy my stitching time, which is often somewhere away from home (ballpark, doctor's office, playground) and if I'm stitching for any length of time, food is involved!
And one more thing ... when stitching large pieces over any length of time, I sometimes wash and iron before I am done. And sometimes it's more than once.
But even if you stitch in a smoke-free, pet-free, food-free zone, needlework always looks better after it is washed and ironed, IMHO.