Imagine living in the [Roman Empire](https://en.wikipedia.org/wiki/Roman_Empire) around 100 AD. The empire controls most of the known world! No foreign power could possibly defeat the empire! The Romans will be in charge forever!

... except we know that's not what happened—the empire declined and fell apart. The fall, however, did not happen overnight. The empire went from prosperous to not so hot to oblivion over the course of centuries.

It doesn't seem hard to imagine what it would be like to live in the midst of prosperity, or what it might be like to live when an empire is in clear decline. 

The middle ground is where it gets interesting. The honest among "the powers that be" would be aware that their civilization is in trouble, while some others would be drunk with power and either not realize or not care that their actions are contributing to the destruction of their civilization.

But what about the people who are not in charge? **How would an average Joe realize that things are going in the wrong direction?** If he knows in advance that things are going south, then he can prepare for both himself and his family.

Some notes:

* I just used the Roman Empire as an example of an empire that declined. Your answer should be applicable to more than just that one empire.
* Examples from the decline of real-world empires are appreciated.
* Our average Joe does not have special access to information about the empire, i.e no brother who is a general in the army and gives Joe specific information about how battles have been going, but he could hear rumors of a battle going poorly.
* Our average Joe doesn't actually have to be average, but he's no Einstein.
* The civilization is still doing rather well, but in the near future (20-100 years) it will be pretty obvious that it's in decline.