Well, there's lots of them about.

Informal singarounds and sessions are fine but I always try to support the official side of festivals as well. After all, the "fringes" probably wouldn't exist without it. At least not to the same extent or indefinitely.

Visitors and festival goers should also try to support the local community too... e.g. patronise local bars, restaurants, shops and so as opposed to stocking up with food and booze from their home supermarkets. Some of them never leave the camp site and/or camper vans over the whole weekend.