While many Spaniards will meet each other with a kiss on both cheeks, this is not common in business relationships unless you know the other party well. It is wisest to offer a handshake, and if a kiss is appropriate, the Spanish party will initiate it. (And note that you don't kiss their cheeks. You kiss the air while touching cheeks.)
Addressing a person
Spanish people have two first names and two surnames, composed of their father's first surname and their mother's first surname. Use Señor (Sr.) or Señora (Sra.) as you would Mr. or Mrs.
In the first meeting, Spaniards will want to become acquainted with you before proceeding with business, so you should be accommodating and answer any questions about your background and family life. Spaniards will really check to see if you are honest and reliable, to know they can place their trust in your products or business before starting a relationship.
It is unlikely that a meeting will stick closely to a detailed agenda. Negotiations in Spain tend to be quite open with one party taking the lead, but agreements can be flexible and you will probably need to persevere in order to ensure that commitments are put into effect. Understand that your goal is to do business in Spain, not to impose a business culture.
If you want to discuss business at lunch, you should mention this in advance so the Spanish counterpart is ready to discuss the issues with you. Meal times in Spain are generally considered the time to relax and enjoy oneself rather than to close deals. More typically, the deals are done at the office, and then after the successful negotiations, you all go to celebrate at a restaurant. If the Spanish party wants to be nice with you, they will most likely invite you to go to a nice restaurant. The one who extends the invitation is the one who foots the bill. Bills are rarely split in Spain, regardless of the circumstance. If you have been invited out, you should reciprocate at a later date, being careful not to give the impression that you are simply 'repaying' your earlier hosts.
The Spanish are great conversationalists, this is how they spend their free time. Ask them about their children or family; few subjects are taboo. The Spanish are proud of their food and wine; you'd be wise not to disagree. Don't be surprised if an evening out lasts until the late hours (nor will they be offended if you leave because you can't keep your eyes open). Spanish presentations can tend to be long-winded; expect it and don't get frustrated. If you're female, don't be surprised if they compliment you and tell you you look good. You can compliment them back if you feel like it or just say thanks. There is no culture of political correctness in Spain. In general it's better to be humble, no Spanish counterpart is going to be impressed by you saying how much better your country works or by you mentioning Spanish red tape. If you don't want to annoy people, don't bring up the siesta/fiesta.
Spaniards do not, on average, speak English as well as a Northern European. Many companies in Spain have staff with good English language skills, but an initial approach in Spanish is more effective, if your plan is to sell to the Spanish, try to speak Spanish.
Spaniards derive a sense of identity from their particular region rather than the country as a whole so you should try to be sensitive to regional differences and to avoid making misinformed comments about a Spaniard's region of origin. There are seventeen autonomous regions, each with a different degree of independence from Madrid, and each has its own individual characteristics; you should respect local sensibilities and manners without recourse to stereotypes or caricatures.
Working hours, holidays
In Spain, the hours that a shop and business may be open to the public are regulated by the government. Shops are usually open from 9:00 am to 1:30 or 2 pm, then from 4:30 or 5 pm until 8 pm, Monday through Friday, and Saturday morning. Large department stores are open all day. Professional offices usually open from 10 to 2, then from 4 to 7, though it is becoming more common for businesses to stay open form 9 to 4, so could soon mean the end of the traditional siesta hours. Banks are open from 9 to 2, then by law, they can choose either to open one afternoon a week, or on Saturday morning. In August, when most people take their vacations, office hours change to jornada intensiva: 8 am - 3 pm.
Lunch is between 2 pm and 4 pm. Most people in Spain eat at home, though in big cities, it is common to go to a restaurant and have a menu (and avoid the double commute). Dinner is generally a lighter meal; 10pm is the normal time at restaurants.
There are national, state, and local holidays. For a list, go to Spain's Social Security site, and click on "Lo más visitado", then "Calendario laboral". When a holiday falls on a Tuesday or a Thursday, it is common in the office to take the adjacent Monday or Friday puente off for a long weekend.
At restaurants, bars, and taxis, it is typical to leave the small change, though you won't get dirty looks if you don't.
Time and punctuality
The famous mañana joke, besides being dull, is also not true. If you want to give a good impression, you should be on time, and can expect that the Spanish party will be on time too.
There is now a regulation against smoking in public places, though as with many regulations, there is some degree of leniency. Spaniards were among the heaviest smokers in Europe, not anymore. Californians will be happier now in Spain, but still some places allow to smoke. If smoke is an issue to you, look for a smoke-free restaurant, bar, or hotel: now you can find them, and of course complain if it is not fullfilled.
At Christmas, most companies give their employees a hamper or basket of fancy foods and drink (cestas de Navidad). It is also common to celebrate a fiesta de Navidad with a lunch in a fancy restaurant. Companies often send bottles of cava, champagne, or wine at Christmas to their best clients.
At the conclusion of successful negotiations, it is not uncommon to give a gift to a broker or professional (including a bank officer) who was especially competent: flowers or chocolates if female, or a good bottle of wine if male. If you receive a gift, you should open it immediately in front of the giver, and say Gracias! Any gift should be a high-quality item, and should be finely wrapped. Companies often send those at Christmas to their best clients. Markenting merchandise will be more appreciated if it is a fine pen or a tasteful desk accessory. You should not give anything too personal or extravagant as your generosity may be perceived as rare or even insulting. If you are invited to a Spanish home, again: flowers, a dessert, or a good bottle of wine is the right gift.
In Spain the look of the person one is doing business with is important. Classic brand names such Loewe, Dior, Chanel or Louis Vuitton are very appreciated, also Hugo Boss, Armani or Ermenegildo Zegna, less so Ferragamo or Coach. Look fashionable and smart if you want to cause a good impression; clean your shoes and get your hair in order. The perfume is important, also the quality of accesories, like a good Hermes scarf or Dior bag.
Men are best off in dark subdued colours: preferably tailor-made woolen or linen suits, and white cotton shirts with silk ties. Women should wear well-cut suits of high-quality fabric. Designer clothes and brand names will be noted with approval. The female business traveller should emphasize their femininity through their immaculate clothes and hair.
Business casual means a clean and fashionable designer cotton shirt and good pants, and of course, no tie.
If an invitation to a party says formal, it means real formal: a black tuxedo for men and a cocktail dress for women, always in conservative colors. For these events, women wear more make-up, and have their hair done professionally. For men keep in mind that the Spanish cut of the suit is different than the American or British cut.