A dream journal helps in many ways, including your efforts for future dreams. Additionally it can help you recall that wonderful lucid, no matter what method you use. Details fade the farther we get from an experience so writing them down while fresh helps preserve them.

But it's more than that...

The very act of writing it down helps strengthen the idea in your mind that dreams are important, that dreams are something that matter to you and shouldn't be discarded as whimsy. Writing them down helps you have better luck with future efforts and increases the likelihood you will remember your dreams in great detail.

Sometimes it's the basics that really count the most.