Ah, the happy, helpful colon. Use this little guy with lists, quotations, or to explain the thing (technical term: clause) that precedes the colon.  So:

Things we need for camping: air mattress, tent, stove.

I love what  Nietzsche said about perseverance: “You can never climb in vain: either you will reach a point higher up today, or you will be training your powers so that you will be able to climb higher tomorrow.”

Life in three words: anything is possible.

Cautions when using colon:

Use it:

After the words “as follows” or “the following” or where those words are implied.

In formal salutations

Where dialog is used (but aren’t bracketed by quotations.  Allen: People of mediocre ability sometimes achieve outstanding success because they don’t know when to quit. Most men succeed because they are determined to.)

Don’t use a colon after a verb.  In other words, don’t do this: What I need: chocolate, punch… (though, I have to say as a side note, not really sure why we can’t do this…seems to make sense to me to list after the word “need” but what the heck do I know?)