If you're unfamiliar with the paleo diet (often referred to as "Caveman Diet") it encourages eating what our hunter-gather “Paleolithic” ancestors ate. The paleo diet focuses on a diet of natural whole foods; meat, fish, fruits and vegetables. Put another way it is a dietary plan based on what people ate prior to the agricultural revolution. Grains, dairy, legumes, salt and sugars are not included.
Great question. Beyond "I have no idea.", the best I can come up with is...
Keep omega-6 consumption low (don't just consume omega-3, eliminate most of the omega-6).
Eliminate grains (with the exception of safe starches like white rice and potatoes, depending on your individual goals).
What else is universally paleo? Don't know.
Try google? But you'll just come up with hundreds of variation, so I understand your confusion.
In essence, the Paleo diet refers to the diet eaten by pre-agricultural humans, which consisted of:
A Paleolithic era diet would have varied significantly between different seasons and different regions. The common theme is that you (or your tribe) would have to catch or gather everything, then cook it over an open fire with minimal implements (or simply eat it raw).
Since not many people intend to give up indoor plumbing, central heating and the Internet when they "go paleo" we run into interpretation issues. I find that people are really good at coming up with justifications for their favorite vice (coffee, dark chocolate, red wine, dairy, coconut oil...) although commonly accepted as part of the paleo diet, none of these things are strictly paleo.
So I leave it to you to do the research and define your own "paleo" diet and lifestyle. You can't go wrong by cutting out the industrial crap and sticking to real foods.
Here are some guidlines you might find useful.
“Eat Like A Predator, Not Like Prey”: The Paleo Diet In Six Easy Steps