I did two days last year with a couple mates. Rented an Airbnb a few miles away on the coast and drove in each day in one car. The queue in to the car parks can cirtainly take a while. Get tickets posted to you rather than pick up in site as again this is a big queue.
As for other hints and tips. Do the super car section last, not first as it’s right by the entrance and gets very very busy in the morning. If your interested in the hill climb cars, when they depart for the start and return to the paddocks is a good time to have a good look and listen to the engines, I found the actual racing up the hill a little dull as they just zip past unless the driver wants to do some donuts on the first corner area.
Look at the time table, if the rally stage is on, get a tractor to the top of the site and watch some.of that and the off road buggies and work your way back through, doing super cars last.
There are plenty of food stalls, but it’s expensive (£12 a crappy burger) so you can take a pack lunch, best food I had was the Yorkshire pudding company? Full roast dinner wrapped in a giant Yorkshire. If your planning on drinking, take your own beer as it’s far cheaper than the bars on site.
Theres absolutely loads to see and do and lots and lots of stalls. Like I said we had two days and still didn’t see everything….lots of walking though so wear good shoes and suncream / raincoat.