I am not experienced, but these are some things that I've come across in my planning:
All National Park campsites on the Cape have to be pre-booked now, so if you are planning to camp in Lakefield, or Cape Melville, Mungkan Kandju, Captain Billy Landing, Iron Range/Chili Beach itself, or go in to Maytown etc...on your way south, you're supposed to book before arriving.
Here is a link to the National Parks on Cape York
http://www.derm.qld.gov.au/parks/list.php?region=59 To help travellers on the road, and because it is a new system this year, they will have touch screen booking facilities at the ranger stations if you just want to turn up and hope that there's a vacant site.
Weipa Camping Ground's website says bookings are essential, but when I spoke with them a couple of months ago, they said that only powered campsites need to be booked.
Eddie's camp at Elim Beach, on the coast past Hope Vale, is supposed to be a great spot as well. Coloured Sands, fishing etc...
Here are his details
http://www.cooktownandcapeyork.com/stay/hopevale/elimbeachcampsiteGood luck with the planning, it's half the fun
Karen