Bring a "disposable" back-pack. I carry a mesh pack that folds up to the size of about 5"x7" and fits into a pocket. In it I carry a snack, small bottle of water, soft drink, and umbrella. Once the drinks & snacks have been consumed & containers properly disposed, I fold it up & stash in a pocket or use it to carry souveniers I purchase. Invest in a good pair of hiking boots that are waterproof. . They will pay for themselves the first time you climb all those uneven stairs or walk along stone/marble floors. Your feet stay warm & dry as well as supported. You'll thank yourself many times over Remember to take bandanas, hats & gloves depending on destination. Carry a roll of biodegradable Toilet Paper. It's small in size, but lasts weeks. Also carry along a bottle of Motrin or IB Prophin; either one elliminates all sorts of aches & pains one encounters during travel. Avoid trying to find film or batteries by carrying a disposable camera. I carry one as a backup to my digital. If I want a photo of myself in front of a monument or historical place, I don't think twice about asking someone to take my photo. Thus protecting my more expensive digital camera from theft. Take along a plastic poncho to protect clothing from unexpected showers. Umbrellas tend to lose their waterproofness after 30 or 45 mn in a downpour. A plastic ponco with hood will shield one from head to mid-thigh. I usually print out some business cards with a destination photo on one side, and my personal info on the other. This helps the recipient remember where & why they got the card. I also take a sheet of address labels along in my guide book. I use them for postcards, or to swap addresses with fellow travels met along the way.