Common preparations include the creation of a clandestine or defensible retreat, haven, or bug out location (BOL) in addition to the stockpiling of non-perishable food, water, water-purification equipment, clothing, seed, firewood, defensive or hunting weapons, ammunition, agricultural equipment, and medical supplies. Some survivalists do not make such extensive preparations, and simply incorporate a "Be Prepared" outlook into their everyday life.
Another concern when you’re lost in the wild is where to procure potable water. Sometimes there will be bubbling streams of crystal clear water rolling down wooded hillsides to fill your water bottle and sometimes you’ll have little more than a stagnant pool standing between you and dehydration. The LifeStraw Personal Water Filter is survival gear that can turn that stagnant pool into a lifesaver.
To me, the best option is to store emergency food. How much? If you have none, store enough for a few days. If you have enough for a few days, get enough for a week. How much you store depends on what time frame you think you're at risk for having to be completely independent. The early settlers of the southwest liked to store enough food for a whole year and still do to this day!