I just received as a gift a bottle of Graham's 20 year-old Tawny Porto. How should this be stored before and after opening? I've never owned port before.
It's my understanding that once opened, unlike wine, Port will keep longer with little deterioration in flavor. Is this true?

Before: Cool, dark place on its side.

After: Seal tightly and place in the fridge. It will last a few weeks. Another trick I've used: take a plastic sandwich bag, place it under the cork with some of the bag exposed. Replace the cork tightly, then seal the edges of the bag off with a rubber band around the top of the bottle. Place in the back of the fridge.

Enjoy that Graham's, it's quite nice!

Thanks sarbuze!