Your camper has to be connected to water, sewer and electrical supplies. Be sure to have the proper extension cords and adapters for electrical. You will need a hose for fresh water. If your camper requires a water pressure regulator, make sure that is stocked as well. You will need appropriate sewer hoses and connectors. Keep a kit in your camper stocked with vehicle essentials like fuses, bulbs, jumper cables and basic hand tools. Be sure you have a spare tire.
Next, stock up on the things that keep you running. If your camper is bare-bones, be sure to stock plenty of water, a cooking stove or grill with fuel and the essentials to deal with waste disposal, like garbage bags, a shovel and a cleaning station. A first aid kit, a fire extinguisher, flashlights, a sewing kit, a lighter or matches and trash bags are essential for any camper. For campers with kitchens, be sure to bring the fuel necessary to run your stove if it is not electric. Stock your camper with cooking supplies like measuring cups, skillets, washcloths, a bottle opener, dish soap, plates, bowls, utensils and paper towels. Have a tool-kit that includes a utility knife and tie-downs on board as well.
Stock up on personal hygiene items like camper toilet-specific toilet paper, deodorant, soap, shampoo, conditioner, bug repellent, sunscreen, a toothbrush for each person, toothpaste and a hair brush. Don't forget the user-specific essentials like denture cleaner, eye drops, contact solution or feminine products. Replace these items once a year. Stock any sheets needed for beds, pillows and blankets. Include towels if your camper has a bathroom.
Now you can start stocking up on the things that make you comfortable. Pack a power-strip or other multi-outlet cord, along with an electric fan and radio. Pack chairs for sitting outside of the camper, along with a folding table and beach towels. To keep the camper clean, stock a hand-held vacuum cleaner, ant traps, a doormat and cleaning supplies. Have entertainment like games and reading material available as well.