Forever vs. Time-bound

Here's the first thing I teach organizations that come to me for advice on their new website:

Figure out which content is 'forever', and which content is 'time-bound'.

Then make sure that you write the 'forever' parts so that they are independent of the moment of reading: Avoid announcements like 'soon' or 'next year' and references like 'the current board'. If the content isn't there yet, just remove it from the navigation and commit to adding it asap - it is far too easy to forget about the In Construction signs all over your website. Even if you don't expect changes, be nice to your visitors and let them know when you've last updated the article.

All other content comes with a date stamp, and can be written with reference to it ("The board meeting today concluded..."). Over time, older content sinks down in the lists of documents, news, events etc. and is essentially archived. Particularly important content (eg. a seminal publication) should be featured separately and linked to from 'forever' or static pages.

What is the first thing you teach?