make sure your boots are made for walking
If you don't have a car, chances are you're walking several miles a day. This is especially true when you're in Europe. Public transportation is great, but I definitely recommend that everyone walk everywhere (within reason. Don't try to walk to a neighboring town or anything.) for the first few days, just to get the lay of the land. It definitely helped me when I was finding my way around during the first weeks. If you're anywhere with cobbled streets, expect your shoes to take a beating. I calculated that I walked roughly 750 miles (and that's a conservative estimate) during my semester abroad, so make sure your feet are ready for 7+ miles a day! Needless to say, you need to treat your feet well to make the most of your travels.
Buy shoes with real soles. I know this sounds like a no-brainer, but take a look at some of the trendier shoes you have in your closet. How much rubber separates your foot from the street? More often than not, the answer is, "Not nearly enough." Having an ultra-thin sole seems practical for packing, but remember: your shoes are not going to hang out in your suitcase for the entire trip. Save weight elsewhere. Don't skimp on the sole. Many women's flats or sandals are the culprit when it comes to flimsy soles, so be sure to invest in some durable shoes before takeoff. You're far better off taking three durable, supportive pairs of shoes than six flimsy ones, especially if you're in a place where uneven cobblestones are common on sidewalks. I found Rothys and I absolutely love them. They're flats that wear like socks and have a real sole! I can't say enough good things about them. You can check them out here.
If you're going abroad for an extended stay, remember that you can always re-sole your shoes. Cobblestones will quickly shred the heels of your boots. Don't be afraid to find a cobbler and have them re-soled. If you look on local expat sites or even ask one of your local friends, they should be able to direct you to the right person. That's the beauty of buying durable shoes. Parts can be replaced without compromising the integrity of the shoe. This is great if you have a pair that you've loved just a little too much.
Material of the upper should be durable. This is not the time to try out some trendy new pleather and cardboard fad. It's just not worth the blisters, which could cause problems for the rest of your trip. Opt for leather, outdoor fabrics, and other strong, sustainable materials that can withstand miles at a time. When trying on shoes in the store, they should be ready to walk ten miles in right away. You should never feel like you need to "break in" your new pair of shoes. Don't ignore the small irritations like rubbing or tightness when trying them on in the store because they will be major irritations when you're on mile four of your six mile walking tour.
Waterproof your shoes before you leave. Life happens, even on vacation, and you never know when you're going to get stuck in the rain. This is an inexpensive way to make your shoes last longer and you can find waterproofing spray at most places shoes are sold. Just make sure you're not waterproofing your shoes the day before you leave, as the spray can take time to dry and you'll often have to do multiple coats. Follow the instructions on the bottle and you should be just fine.
Traveling in Europe is not the time to bust out a new pair of stilettos. If you look around, very few women are sporting sky-high heels because they're so impractical to walk in. Favor function over form when picking your shoes for a trip and think about whether or not you'll be able to walk on cobblestones in the shoes you want to bring. Try to find a comfortable flat, a sandal, a boot and a more athletic shoe that isn't a white sneaker. You should be pretty well set for a long-term trip with these four pairs. I did my semester abroad with four pairs of shoes and I really didn't miss more options. But if you have an event where you absolutely cannot go without a stiletto, wear flats to the event and change once you get there. You'll likely be able to leave your flats at the coat check.
None of these options replace sound orthopedic advice. If you have any medical problems with your feet, legs or back, please talk to your doctor. I'd love to be an expert on everything but I'll be the first to admit that this is simply not true. The bottom line is this: shop smart when you're looking for shoes and opt for function and high quality materials over how cute they are. While both are important, your shoes should NEVER be the focus when you are traveling. If you can ignore your feet while running around your new destination, you've found the right pair for you.