The elemental luxury of linen is exactly itself, simple and timeless. Tactile, strong and visually pleasing, it pampers you — you don't need to pamper it.
Do up any buttons.
Machine wash with a mild detergent (definitely not Tide). I use cold water to be energy efficient but it is safe to boil-wash linen.
Never use bleach (not even on white linen).
A Biz soak is fine as long as it is dissolved first and used on wet fabric.
Never pour detergent directly onto dry fabric — always dilute the detergent first. The fine print on the back of the detergent bottle is there for a reason.
For spot removal I suggest mild detergent or bar soap rubbed into damp fabric. Or Shout.
Fabric softeners: No. They were invented for synthetics which can smell, are not needed for natural fibers, and are actively unhealthy. The plasticisers they contain gum up fibers and dryer filters alike.
In a dryer, use a medium setting, dry the linen by itself and don't over dry. Shake it out while still damp and lay it flat. It will, by nature, have a soft, complex texture.
If you accidentally overheat, crowd or overdry your linen and it becomes wrinkled, dampen it and the wrinkles will relax. For a small wrinkle (where it was pegged on a line, for example) dampen with a spray bottle of water, or just let it relax by itself over a day or two.
For preference, line-dry and let fresh air, wind and sunshine do their work.