Fire, shelter, water and food, signaling ability and first aid are the key essentials to surviving in the wilderness. Don't get stuck outdoors without a basic kit geared around these needs. Know how to use the items in your kit before an emergency strikes.
The single most important skill to surviving in an urban environment is an understanding of psychology. Know how predators think and what they look for in a target. Use this knowledge to safeguard your home, avoid problematic situations and handle them safely when they arise. Knowledge of physical self defense is useful, as is the ability to predict and avoid situations where such skill is required.
Stockpile non-perishable foods, drinking water, first aid supplies and fuel; obtain a battery-operated radio and batteries. Learn the basics of gardening and food preservation. Investigate the options for generating your own power from a renewable source. One or more firearms are essential for hunting and self-defense; take a training course so that you'll know how to use them safely.