I don’t know about all systems, but for us (and most other rigs we know) its a family thing. Try and find out who some local party organisers are and make friends. Offer help with organising, site finding, or just generally lifting stuff 🙂 Think of anything that you might be able to offer the crew, look at what your skills are and how you could help.
Thing is, there are lots of dj’s out there and a lot of them are of a high standard. If we gave everyone a set who asked there would be no room for the people who put all the effort and passion in to making the parties work.
Alternativley, hang around the system until the late hours of the next day and wait until everyone is too mangled to play and you might be able to get on. But don’t pester!
Hope that helps mate. And I hope I didn’t sound patronising because it’s not meant to be.
Sound advice Bio-Tech, I’m with you here! A lot of rigs are very suspicious of new comers and certainly won’t let you do a set until they know you are safe and are playing in the same court as them (so to speak) get involved with your local scene and see how things develop.