When to use "just"

Solution 1:

I'd say a good rule of thumb is to use it when you need it for clarity or to add a special emphasis.

There were just three jars of honey left.

This is different from

There were three jars of honey left.

because it gives the sense that three jars of honey is not a lot, or at least that you don't think it is.

So the answer is no, don't give it up entirely. Just trust yourself to use it less. Think of it as dieting. If you have the willpower, you can write lean sentences.

Solution 2:

As other words, use it when it adds a meaning to the sentence, and not just to use it.

A just and democratic society (it is different from a democratic society).
We all get our just deserts (it is different from we all get our deserts).
I've just seen the local paper (it is different from I've seen the local paper).
They were just interested in making money (it is different from they were interested in making money, but it is similar to they were only interested in making money).
They are just great (it is different from they are great).
"Simon really messed things up." "Didn't he just?"

_{[Reference: The New Oxford American Dictionary.]}