Don't Judge Me, Bro

We're looking at The Sermon on the Mount, and here in this one section, there's evidence that this really IS the most famous sermon ever preached.

It's so ingrained in the cultural vocabulary of the Western World that I dare say most people in our time and place, even non-Bible-readers have heard of two phrases in this section: the Golden Rule (v. 12: "do unto others as you'd have them do to you") and "Judge not lest ye be judged." (v. 1) So what do these words mean? How do they hold together with the main themes of the Sermon on the Mount and what DO they mean for life in your home, your office or workplace, neighborhood and church?

Specifically,

1. What does it mean/not mean to judge people and why's it so hard to stop?
2. What's the Key to avoiding it?
3. What's the Alternative (in practical terms