Clean your Space *
It's the part, that's next to your parts.  Keep it clean and you and your passengers will be very happy.  Sometimes I keep mints in my car for passengers.  No chocolate though.

Take out the booze:   Get some rubbing alcohol at your local drugstore.  Take a soft lintfree cloth (mini-microfiber from YoSteve works well) and wipe down everything plastic and hard.  This not only cleans but disinfects.

Suck out the dirt:  Use your vacuum, or buy the Hang -up 1 gallon, 1.5 hp Shop Vac at Lowes for $17.99.  Make sure you get everywhere; go over the parts that aren't dirty.  You can also use this opportunity to suck up any of the dust on your dash, cupholders, etc.

Clean the Carpets:  Use a terry towel and some of that rubbing alcohol to surface clean your carpet.  If you need stronger stuff or are looking to get rid of odors, check out some auto carpet shampoo.

Dress up your Dash:  Two choices here 303 Aerospace protectant or Black Magic Semi-gloss Dashboard protectant (make sure you get this by the exact name, no silicone, no professional, no shine, no waterless formula).  Use a sponge and apply, if you get streaks after 30 minutes dry time, take a microfiber and buff off the excess (shouldn't be any).
Jason's Detailing Corner