To make things more vivid I simply say "increase lucidity" and the colors then pop (i.e., become deeper than you've ever seen them).

I also recommend that you "plan" what you'd like to do once you're lucid.. go over it in your mind while lying in bed. Rehearsing what you'd like to do will ensure that you're not just wandering aimlessly wasting the experience.

One cool thing would be to ask to see/meet/talk to your Spirit Guide of Pure White Light!

Clairity