What you pack will depend on where you go and what time of year. The number one thing to keep in mind if you're backpacking is PACK LIGHT!! Bring one pair of VERY comfortable walking shoes (bad shoes can ruin a vacation). Sneakers are great, but they definitely signify "tourist." Don't bring shampoo for 3 months, it's easier and not a great expense to buy them as needed. Dress in layers to take more off your shoulders and to be prepared for a mix of weather. Bring shirts with sleeves and long pants (you'll look less like a tourist and many sacred places require shirtsleeves).