Must have:

Wallet and/or purse and cash (we often forget the most obvious things)

Credit cards and/or traveler's checks (plus list of numbers of both)

Car and house keys (plus duplicate sets kept in different bags)

Eyeglasses and/or contact lenses (plus lens cleaner)

Medical insurance cards, list of phone numbers

Prescriptions and other medications

Itineraries, tickets and reservation confirmations

Maps and directions

Camera, film, digital camera memory cards, batteries

 Must do:

Pick up trash / Remove trash from home before departure

Buy travelers checks

Tune-up car, check tires, battery, major fluids, brakes etc...

Replace expired prescriptions and medication and replace expired sunblock, most SPF lotions lose potency over years time

Replenish Toiletries kit

Hold incoming mail and newspapers

Notify neighbors of your vacation and give phone # for emergencies

Mow your lawn just before you leave

If you're leaving your car, leave it parked in the driveway

Lock all windows and doors before you leave

Unplug small appliances

Turn off AC/Heat

Make arrangements for any pets you have