To start a walk at the top end of Fraser Island requires a bit of planning - if you can't afford a helicopter or light plane flight over, the cheapest access is via the barge at Inskip Point. We caught a local taxi from Rainbow Beach to the barge and were picked up by the only taxi (4WD) on the island for the 70km trip to Indian Head. This is an interesting way to get a feel for the beach down which you will be walking over the next few days and the cost can be quite reasonable if you are a group. Standard taxi rates do apply. If you are walking north-south, you will either have to carry a heavy load or leave food caches. We left one cache buried at Hook Point on the extreme southern tip (you may prefer to do this on the mainland side of the straight at Inskip Point or even arrange to leave it with the barge operators as dingoes could dig it up - however, we wrapped our cache securely and it only contained tinned food and a 5 litre plastic container of water). Our second cache we left with the managers of Dilli Village and our third cache at the office of Happy Valley Resort (this contained most of what we needed for 5 days of camping on the Fraser Island Great Walk). We took a fourth box of food up to Indian Head with us and generally ate very well. There are small stores at Cathedral Beach and Happy Valley to top up your supplies as well.
On the beach part of the walk, you can either pitch a tent on the beach (in designated areas) or National Park or private campgrounds at Waddy Point, Dundubara and Cathedral Beach (there is a store at the latter). If you are camping, you need to book sites through the Environment Protection Agency, for both the Great Walk campsites and for beach camping. For a bit more comfort, you could hire a cabin at Indian Head, Cathedral Beach or Happy Valley Resort. We found a two night restover in a cabin at the Happy Valley Wilderness Retreat a perfect way to prepare for the Great Walk section. The National Park provides walker's campsites at convenient (apart from "Not Lake Waddy") locations along the track, with good tent-sites, dingo proof storage boxes or fencing and water. If you don't want to carry food for all that distance, the island taxi service will do a food drop to Lake McKenzie.
Most people seem to walk the Fraser Island Great Walk from south to north. If you do walk it in the opposite direction as we did, leave a good supply of food and drinks at Dilli Village (there is no store there); it is an oasis after the 80km walk and the well-equipped cabins mean you can enjoy a decent meal and a cold drink for a day or two before heading on. The inland track from Dilli Village to Hook Point is a bit overgrown in parts, but is shorter than walking the beach - make sure you set out early to reach Hook Point before the barges stop operating. Inskip Point on the mainland side has a long stretch of campgrounds, with toilets but no showers. They say that there is no drinking water, but the toilet roofs catch rainwater for washing hands - at a pinch you can boil this or treat it.
Rainbow Beach has every type of accommodation from camping to backpackers to luxury apartment - the backpackers is certainly the most lively! From Rainbow Beach south, you will have to camp and you need to book permits through the Environment Protection Agency for camping at Freshwater Creek, on Teewah Beach or along the Noosa River. There is not a lot of reliable water between Freshwater Creek and the Noosa River and you will need to spend one night out, so you may have to carry a fair bit of water along this stretch (a bit frustrating when there are lots of car campers along the beach, but we didn't want to bludge off them) There are a number of designated campsites along the Noosa River - we found that Campsite 2 was the smallest, least crowded and most pleasant, being right on the river. The tracks are all well-marked - and there was only one tricky section, the turn off to climb up and over the Cooloola Sandpatch from Teewah Beach. This is not marked at, but the overgrown track heads up a creek at the southern end of a small valley with low eroded sand cliffs (S26º11.81 x E153º05.05). Finally catching the cruise ferry out from Harry's Hut to return to Noosa, not only avoids walking through a lot of urbanised landscape at the end of the trek, but a barbecue lunch with red wine is a great way to end a long walk.
On Fraser Island you can get away with two maps; the Hema Fraser Island regional topographic map(1:130000) and the Great Walk topographic map (1:50000) for a bit more detail. Track notes are also available for the Great Walk and both maps and notes are available from Queensland Environmental Protection Agency offices. On the mainland side, we managed with the Cooloola Section and Noosa River Park Guides from the same agency. They are not topographic maps, but then my GPS provided that information. We actually did the walk in our trekking sandals, great on the beach and in the dunes, but not so good on the inland tracks, which in parts are covered with twigs and branches that can give your toes a good scarification. Boots are probably best here, even though you are walking on sand all the time. One final and important point - we would recommend doing this walk before October to avoid the high humidity and most of all, the March flies, which can be distracting to say the least. Definitely include insect repellant in your pack.