The CDC recommends that planning ahead for zombies is really no different than preparing for other types of disaster. The same basic principles apply.
Planning ahead for any type of disaster or emergency requires the same basic items: Food (nonperishable of course) and water (one gallon per day per person), medications (both over the counter and prescription medications), tools and supplies (basic stuff like utility knives, duct tape, radio, flashlights, batteries, etc.), sanitation and hygiene (soap, shampoo, bleach, feminine products, towels and lots of toilet paper), clothing and bedding (extra clothes for every family member, blankets), important documents (copies of birth certificates, social security cards, driver’s licenses, insurance cards, etc.), first aid supplies.
As with any other emergency, in the event of zombies you should have an emergency plan that includes evacuation plans and a safe place to get away from the zombies.
According to the CDC blog, if a zombie apocalypse breaks out, the CDC will investigate the event just like they would any other disease outbreak. CDC investigation and assistance would include “consultation, lab testing and analysis, patient management and care, tracking of contacts, and infection control (including isolation and quarantine).” Just like any other disease outbreak, the CDC would try to determine where and how the outbreak started and would make every effort to determine how to best deal with an outbreak of zombies.