worldclimb2119980 wrote an answer about Osprey Packs Aether 85 Backpack - 5000-5400 cu in on April 27, 2010
First time I went traveling I had a huge backpack crammed full of everything I thought I'd need. A buddy who had done it years before said I should go with nothing, buying what I needed along the way. At the time I thought he was crazy, after my first trip I think he was right. 2 months into your trip you'll be sending half your stuff back or on to another destination.
Buy things you need in cheap countries. Clothing in Thailand is a buck an item for the same thing that'll cost $20 here. I got a fleece jacket in the chilly Thai mountians for $3. I passed it on to another traveler at the bus stop when I got back to the beach.
After a while I ditched the big backpack altogether. I traveled in India for months with only a day pack (15L North Face bought in Bangkok for a few bucks, and still going strong years later). I had one extra set of lightweight long sleeved clothes for the evening and I hand washed my stuff every day in the shower. I traveled with a bunch of camera gear including a tripod and digital SLR, which made up half my pack.
If you're heading to a more expensive country, look to the second hand/thrift stores as stuff can be bought for a bargain often with tags still on it. Online classifieds sites will provide all you need too! Don't forget couchsurfing.com too.
Big packs need to go on the roof of buses, into the luggage sections of trains and into the belly of planes. Day packs sit on your lap. You never need to worry you wont have your stuff when you get to your destination.
Travel ultra light, leave gadgets at home, and you'll enjoy the experience a lot more. Have a great time, and don't plan too much ;)