Battery operated lights only for inside the tent, and always leave barbeques/oil lamps or anything that involves gas/oil/burning outside the tent. Not only are they an obvious fire risk but they also pose a big CO risk.
Cool boxes are good for storing food, keeps it dry.
Don't put anything within a good few inches of the tent edges, it will end up soaking by the morning, water proof tent or not. Avoid also touching the sides of the tent as water will come in, usually from condensation.
Plastic boxes for dishes, storage, clothing to keep stuff dry and organised
Wooden sticks to place shoes upside down (especially good for welly boots), dries them out and stops spiders etc from moving in.
Torch by the door, next to shoes on sticks (have a grab and go bag)
If you don't fancy seats, rolled newspapers in an overlap fashion covered in bin bags and stuck with masking tape's always good.
Take tent patches for repair in the possible event that the tent rips, plus spares of everything especially pegs. Spare rope/strong wire for guys. Waterproof spray for the tent.
Take plenty firelighters, also fire proof gloves, and sand/water buckets if you plan to cook on a fire.
Take a first aid kit, spare fully charged mobile in case you can't charge it and need one.
Plenty of spare batteries.
Plenty of loose change for token washers/driers.
Cook simple stuff - e.g. spag bol, salads, pasta dishes. Have big breakfasts and lunches, lots of snacks - camping makes me very hungry..
A groundsheet, fleece, then a raised bed, with another fleece layer is good for warmth. To save time on the first night you can make bedding rolls and stuff jammas in them etc.
Washing lines and the like can be easily made if you have some good strong bits of wood (tree branches etc) and spare rope.
Make ground rules if you want to avoid tent mess - e.g. no shoes to be worn in the tent..
Waterproof trousers and macs are fab for sudden downpours.
Plan day trips or take indoors stuff if it rains - e.g. colouring books, simple toys for kids, kindle etc for adults.
Have camped for years and years since I was tiny, did loads of camping with girl guides in the green bell tents where the sides are rolled up daily and everything has to be packed up each morning!!