Go with good friends.
Only go to a site that allows real campfires, hires out firepits and sells wood and kindling on site. It must also have a shop to buy fresh milk.
Allow a free day's annual leave before you go to pack at leisure.
Have a big porch / gazebo / event shelter for cooking, and for sitting relaxing out of the sun and rain. (Too much hot sun is not fun).
Wind is worse than rain - don't go if strong wind is forecast.
Absolutely minimal cooking - cereal for breakfast, salad or sandwiches or wraps for lunch, packet of ready-meal quick-cook pasta or rice or couscous or noodles for evening, or go out to eat a proper meal, or get a takeaway. Have loads and loads of crisps, fruit, biscuits and cereal bars ready for snacking. Not chocolate-coated if the weather will be hot.
Always wash up before bed so that you have stuff ready for the morning.
Take proper mugs and glasses, not plastic or metal 'camp' stuff. Ditto proper pillow. If you are getting older and/or a bit stiff, have chairs and a table.
Pegs to dry things on guy ropes.
It gets cold at night - wear warm clothes and woolly hat around the fire, even in summer, and sleep with lots and lots of layers (either wear clothes in bed or double up blankets/sleeping bags).
Bucket for night wees, or pitch close to the loos.
Accept you will be wearing smoky grubby outer clothes during the day, but keep some 'fresh' ones smoke-free to change into for days out or evenings off site.
Wellies, as the grass is usually wet with dew first thing even if it doesn't rain.
Don't rush anything - take it easy and slow down.
Go for at least 6 or 7 nights, or all the effort won't seem worth while.