Judge not, that ye be not judged. For with what judgment ye judge, ye shall be judged: and with what measure ye mete, it shall be measured to you again. Matthew 7:1-2
A pattern in scripture is the relationship between commandment and blessing. And this particular commandment is crystal clear.
The commandment is to not judge others. The blessing is that you won't be judged.
Then, just in case we don't quite get it, the Lord amplifies it for us. However we judge others, that is the judgement that will be applied to us.
How do I want to be judged, when my time comes? Very leniently. I am fully aware of all my failings and shortcomings as a person, and I would very much like as much forgiveness as possible. So all I have to do is be forgiving of everyone around me.
I should love everyone, accept them no matter what, help them in any way I can...oh, wait, these are the Christlike attributes that are listed as the rest of Matthew Chapter 7. If I can do this—if I can see everyone else in the best possible light and recognize that every person around me is a child of God—I'm just living the second great commandment to “love my neighbor as myself”. Somehow all the commandments seem to lead back to that.
As simple as this commandment is in theory, it's still difficult in practice. Not that I'm a hugely judgemental misanthrope, but when I'm tired or frustrated or just not coping it's easy to try and blame people around me for my problems. Wrong, but easy. So I'm trying to apply this “Judge not” mindset even in those moments. I'm trying to love everyone even when I'm having a hard time loving myself.
And, failing that, I'm trying to get myself to a quiet place, away from others, until I'm in a better mood and able to be nice. Yes, I put myself in time out.