Whenever possible, schedule appointments (say, your kids' haircuts or doctor's visits) back to back or simultaneously.
Become the queen of calling ahead. "Call in advance for restaurant seating, call the store before you go to make sure it has what you need, call before appointments to see if the doctor, hairstylist, or whoever is running on time," Novak says.
For away-from-home emergencies, pack your trunk with an extra diaper bag stocked with diapers, wipes, a blanket, and a change of clothing.
Don't throw away those return-address labels that keep coming in the mail -- stash them in your bag. "The next time you need to provide your name and address, simply stick on a label," Novak says.
Keep a small trash bag in your car. When I pull into the driveway with my kids asleep in the backseat, I use the time to gather wrappers, cups, and other trash that has accumulated in the car.
Also store a small bin (a folding fabric cube works well) in the car to gather toys, sippy cups, and other items that belong in the house. Toss the items in the bin for easy transport inside.
Hire a babysitter or swap babysitting duty with another mom so you can quickly knock a few to-dos off your list without the kids in tow, Novak says. "If you've already booked a babysitter for a particular event, fit in an errand or two before returning home."