There are a lot of things you really need, special when the weather is not nice ...
It's happen a lot of times, that short Rain attacks are coming, so you need:
Good Walking Boots, maybe Military or for the Mountains
Long Trouser, the best would be Leather (it's going cold after 21.00)
A jacket, Leather would be the best
Rainclothes could be also an Alternative.
Also some warm clothes for the evening and sleeping, it could be very cold sometimes.
If the Sun is shinning, you need a short Trouser.
Something for the Head is always good, special when you sleep in the Sun ...
If you don't drink Beer or Cider all the time, you need something for the water (there are some places inside the Festival Area where you get water for Free), but things you could trough are not alloud.
Very Important is a good Tent, Sleeping Bag, and something for under the Sleeping Bag. A little chair for the Camping is not bad, special when it was rainning before. If you come with a lot of people and a few Tents - take a Party Tent with you.
All the eatting stuff you can find is very tasty, but it's always good to have some Reserve Food with you.
I cannot give Tips about the Alcohol, cause everyone likes different things, and it's differnt how much ...
We take Vodka, Wine, and Beer with us, the Cider we catch from the System Bolagen in Sölvesborg. It's very closed to the Train station.
And there is also a Bankomat around the corner. (No Bankomat in the near of the Festival Area!)
And it's always funny to have a little Camera with you.