Get a copy of the Destination Darwin Visitor Guide as soon as you arrive - you'll find it at hotels, hostels, airport etc. Or at the Visitor Information Centre
This booklet has everything in it - hotels, shopping, tours etc. But, what I loved the most was the maps. Small, easy to read and easy to put in your pocket
It's well worth going to the Visitor Information Centre in Bennett Street, downtown. Inside you find a large array of brochures on Darwin and the Top End wider region. Also, several Information Officers, awaiting your arrival and eager to help. These people are well trained and very knowledgable on both the local information and booking and travel arrangements. Anything they don't know, they can find out at their fingertips.
It's really beneficial to your visit to Darwin, to read up about history and culture before you set out exploring. You can get lots of material for this at the Visitor Information Centre.