I LOVE Mary Ellen's Best Press but it doesn't seem to be as effective on linen. To return it to it's nice crisp finish after washing I used good old Niagara spray starch.
If appropriate use spray baste. I prefer to sew baste because I'm freaked out by the chemical smell of basting spray. There's no quilting on these napkins but when quilting my Easter table runner I ended up ripping out all the sew basting and redoing it with spray baste to give it more body.
Pin twice as much as you normally would. Linen isn't "sticky" the way cotton is so it shifts a lot more when sewing.
Edited to add: Napkin week tutorials are now available...