No matter how hard you laugh, this could happen one day. Our world is forever changing and new drugs are being made, something could go wrong and if we ever start testing on humans (dead of course), could become undead and bite someone and then BAM, zombie apocalypse. Humans do not know when to stop exactly, so we are forever changing and improving products. A big zombie apocalypse cannot happen overnight, so you have time to get your shit together and get all of the items you will need.
Step 1: Watch Zombieland
Probably one of the best, most informative movies of all time, for something that could ACTUALLY happen. There are 11 steps, follow them all.
Step 2: Check ALL social media
If an outbreak like this were to ever happen, it will be all over social media. Check everything, even Facebook.
Step 3: Make supplies your first priority
Make sure you have everything you NEED, not everything you WANT. You could be hiking in the woods at some point and your hair dryer or makeup is not needed.
Step 4: Stay close to home
This does not mean to stay there when zombies are knocking down your door, stay in one place as long as possible, don't make too much noise and do not go exploring. If you do go exploring, make sure you don't go alone, it's better to travel in numbers.
Step 5: DO NOT go to Walmart
Short term, this seems like a good idea because there is a lot of food, but long term, you will end up dead. Everyone and their mother will be at Walmart trying to get supplies, it will be a worse form of Black Friday.
Do not go and be all friendly to everyone you meet along the way, sleep with one eye open, or don't sleep at all.