Don’t wear high-heels. Your experience will be way more enjoyable if you use more comfortable shoes. A big portion of Portugal’s urban areas like the capital, Lisbon, are paved with sidewalks made of easily damageable basalt cubes. In other words, there are probably cracks and your heels will surely get stuck in them. So, even when you’re headed out, it might be a good idea to stick with your flats.
Don’t talk in Spanish. It seems like an obvious one, but it isn’t for a big part of the tourists that visit Portugal. People in Portugal speak a different language, Portuguese is not a dialect of Spanish! If you speak in Spanish to anyone in Portugal, most will probably understand you, but some people might be uneasy to help you or even feel insulted by that. It's always a matter of politeness to ask if the person speaks a certain another language, like Spanish. Besides, unlike Spain, the Portuguese they don’t dub their movies, everything is subtitled. This means the Portuguese are familiar with English language, they might not understand everything but they will do our best to help you, just remember to be polite and ask if they speak English, or Spanish or anything else. The best way to show respect to a native is trying to speak their language, badly pronounced Portuguese is still way better than spotless Spanish when talking to a Portuguese person.
Don’t count your calories. To put it simply, Portuguese cuisine is amazingly tasty. Traditional dishes like francesinha or the country’s myriad of takes on enchidos are going to blow your mind. Then, dessert will send you to another world. So, remember that you’re on vacation and try to relax. Otherwise you’ll miss out on something truly delicious.
Don’t overlook the wines. Where some countries specialize in beer or whiskey or vodka, Portugal specializes in wine. There are dozens of different labels within the country creating any taste of wine you could possibly imagine. A sizable portion of these wines are delicious, so be sure to try some different kinds of wines while you’re in the country.
Don’t eat an early dinner. If you’re planning on taking advantage of the Portuguese nightlife – and you absolutely should – try grabbing a late lunch and then eating dinner around 9 pm If you eat any earlier, you’ll arrive at an empty bar because they don’t start filling up until around 11.
Don’t pass up the opportunity to surf. Not only does Portugal have some of the world’s best beaches, it’s also got one of the most surf-friendly coastlines in the world. Measuring at nearly 500 miles long, the Portuguese coastline boasts solid surf all year round.
Don’t take the tram during rush hour. The electric car is one of the more unique modes of public transportation that span Lisbon. It’s fast, cheap, and safe — which is why a lot of locals tend to take the tram as a part of their daily routine. You don’t want to be a tourist in the tram who’s ruining some poor commuter’s evening; instead, take the tram in the morning or afternoon in order to avoid the crowd.
Don’t go in July or August. Those two months of the year are the driest, but they’re also the hottest and busiest months of the year. If you plan to visit during the off-season, you’ll find the prices more agreeable and the beaches a little less crowded.
Don’t forget about Coimbra. If you’d like to get acquainted with a mid-sized city that’s simply dripping with old world charm, Coimbra is it. You should plan to stay for at least a few days, wandering around the beautiful little town that’s home to one of Europe’s oldest universities as well as several historical sites that will simply astound you.
Don’t be cocky about your swimming skills. While you should definitely visit the beaches, and trying the water sports is always fun, don’t forget that you’re in the Atlantic Ocean. Some beaches are rimmed by large rocks and others, such as Nazaré and Peniche, are home to massive waves that caution even professional surfers. Do a little research before heading out and look for the flags to get an idea of the conditions.
Don’t raise your voice in public places. The Portuguese are polite and calm people, any showings of the “too much” attitude will not be appreciated, especially if you’re drunk. Don't forget to drink responsibly, too. Portugal is a very safe country and tries to maintain its status as such.