I always keep my consoles horizontal. Though vertical position is more space friendly, physics would tell you it's not stable that way. Also, if you should try to clean your CDs, say thinking it's dusty and stuff, use a soft cloth. Try going for CD cleaning towels. Don't try tissue. Please. If you don't have those, grab the ones used for glasses.
DON'T put any liquids on it save the CD cleaning stuff. Though I really don't trust those. Most of the time people have the habit of wetting the thing then wiping, turning the dirt which could have been dry wiped into something short of dust mud. X_x Sorry for the lack of a better term there.