Backpacks!
If you are backpacking through Europe (or any other continent) having a decent backpack is vital. If you are physically going to be doing lots of walking and hitch-hiking stick to a bag that fits comfortably on your back and has different compartments, so that you can easily seperate your things. When buying your backpack, ask the store assistant to show/explain to you the correct way to pack it - in other words - where should you pack the heavy stuff and where should you pack the lighter stuff etc. This will make carrying a lot easier. Also try it on with some things inside and make sure the straps adjust comfortably. You will seriously regret buying a bag that will be uncomfortable the whole time.
If, like me, you will mostly be traveling by train, bus or plane and are staying in places very close to the stations or airports, get yourself a backpack with wheels. Yes, they make those now. They have all the same traits as a traditional backpack, but have wheels and a handle that pull out, making it ideal for wheeling around airports or walking down the road to a hostel. However, due to the shaft down the back making it possible to pull the bag, they are extremely uncomfortable on your back for longer periods of time as I discovered. You can easily manage them on your back for short periods, but they fail to mould to your backs shape and thus can be rather difficult to carry if you are walking around for hours on end. Luckily I only had this problem once, but quickly learnt my lesson.
This is when your day pack comes in handy. Take big enough a daypack that it can fit into you backpack but also be big enough to hold a decent amount of stuff, not only for day time trips, but also if you feel like venturing off and spending a night somewhere, you won't have to take your main backpack.
It's important to find a backpack that suits you and won't start bugging you 2 days in to your trip.
