Drink plenty of water; at least one litre of water for every hour of walking in very warm weather. Ensure you have an adequate fitness level for the bushwalk you plan to undertake.
Avoid walking in the hottest part of the day or walking alone, register with the overnight bushwalking register if you plan an extended walk. Carry a map of the area you're walking/camping in and know how to read it, tell someone your plan and when you expect to return
Bring a DEET based repellant if camping or walking in the evening.
Snakes can be in the long grass, and crocodiles in the waters not declared safe.
fees/permits
There is no entry fee for the National Park. Camping fees are charged per person per night.