You will need to think carefully about what clothes and equipment you need to take with you. Bear in mind that many things are cheaper to get overseas and there is a tendency to take too much. gapadvice.org has a check list at: http://gapadvice.org
Look at these sites for suggestions on such items as rucksacks, sleeping bags, clothes, footwear and medical kit:
Travel Equipment Specialists
www.travelwithcare.com : offering 10% discount.