Many sit-down restaurants take the mystery out of tipping by including a service charge in the bill. Study the menu for words like “service compris” or “servizio incluso.” An additional tip is not expected in these cases, but if you liked the service, simply round up the bill a bit (if your check is 18.80 euros, leave 20). This varies from country to country, so get advice from locals.
If you're looking for a quick bite, you have plenty of options — every country in Europe has its own cheap and delicious street food. In Greece try the corner souvlaki stand. For fast-food Istanbul style, grab a fishwich at the waterfront, fresh from the guys who caught it. Order up a razor-thin crepe from a street vendor in Paris and then choose a filling to make it savory or sweet.
If you'd rather take a seat while you eat, there are lots of casual bars and bistros. Eating at a corner cafe costs only a little more than lunch at a fast-food joint, but you'll be chowing down on local fare that's typical of the region.
One of the best examples of this is in Spain. Every town tempts you with tapas bars, where you belly up to the bar and just point at appetizers you'd like to try. In Denmark, I love the traditional open-faced sandwiches, with simple toppings elegantly perched on a slice of bread. In Bavaria, there's nothing more local than a knuckle of pork, spiral-cut radishes, sauerkraut and a huge pretzel.
When I'm enjoying a delicious meal, I always appreciate hearing the quiet murmurs of other diners around me. It lets me know that I'm among like-minded souls who treat eating as bliss. Communing with others over good food, served in a setting respectful of tradition and place, is cultural tourism at its tastiest.
Rick Steves (www.ricksteves.com) writes European travel guidebooks and hosts travel shows on public television and public radio. Email him at firstname.lastname@example.org and follow his blog on Facebook.