Not sure about camping as didn't but can say this...
DO: get kangaroo fan vision thing. Two people can share one. It's surprisingly hard to get what's happening round the other side of the track when used to watching on tv
(If not in a covered stand) take ponchos, camping chairs, wellies. It may well rain. Also warm clothes if not hot.
(If In general admission) get there early on race day. We got there at 6am managed to stake out a position at the front in the concrete area at luffield (which btw I would recommend as a place to watch as the drs Zone has been on the preceding straight last two years, saw lots of overtaking)
Go for qualifying too, but maybe not the days prior unless your really into it? Practice is less fun to watch especially at just one corner
DON'T: expect it to be a short journey home... Took us 3 hours to drive a few miles. This was a bad year as the council closed one lane of the duel carriage way out on that weekend... Seriously. Yeah so expect that on the way home.
Expect fans to be intelligent enough to watch the race rather than blow those god damned horn things every. Single. Time. Lewis Hamilton drives by, even when doing nothing. Seriously, every lap.
It's a great experience :) I'd say having been in the stands (comp tickers through DH work) and general admission the only benefit of the stand was no rain on your head and a slightly elevated view. If you work out where you want to be and get there early though general admission is a very cost effective option.