If you can get grass fed and or organic Meat at a reasonable price then definitely go with grass fed, not all of us have access to this meat or it's out of reach of our budgets. Fear not, there are ways around this at least to some extent anyway, if you're a hunter it's easy, you're eating wild meat, wild meat is grass fed and whatever other natural goodies they forage for. Stay away from all Genetically Modified Foods (GMOs)
Always Natural, no Genetically Modified GMO's, grow your own if possible, farmers markets are a great place to source your food from.
Nuts that are Paleo approved make great snacks, though if weight loss is your goal, best to go easy, or not eat them at all.
The Image below is a screenshot of my actual weekly shopping list, it's not a bad guide.
You can find a list of foods at the following link