I think the other cardinal rule is "only one item of linen at a time".
Linen top plus linen trousers/skirt = scrunchtastic.
What annoys me about linen is that in photos it looks artfully creased, but when I wear it is goes unattractively creased - knife creases around lap, saggy bottom/knees.
My best linen trousers are, ahem, a "linen mix".