Don't be surprised if that little, (seemingly) sweet old lady pushes her way in front of you when you've been waiting for 10 or 15 minutes. And don't be surprised when they attend to her before you. If you're in a store talking to an employee and someone has a question don't be taken aback if they interrupt your conversation to ask a question. I don't recommend you break in line, too, but don't be afraid to push your way through a crowd to get to where you need to go or speak up a little when you need a question answered.
Remember that saying you always hated hearing from your parents and teachers? Try and think of this often before you come here. Many Americans and others feel entitled to be treated equally, but that may not always be the case in Spain or Sevilla. The bartender may serve his friends or regulars first even though you've been there longer trying to flag him down. Some people may get olives with their beer while you get only the beer. They may even serve others larger portions of tapas. The store employee may first serve that person who broke in line right in front of you (see below). The person behind the counter in the hardware store may decide they don't have what you want even though you know they do. Someone in El Corte Inglés may tell you there is no way to connect a DVD player to your type of television when there are several ways (hint to the fellow who told us this - I'm watching DVDs just fine on my type of television). These examples are exceptions, not the rule, but they do happen.
You read this everywhere I'm sure but I'll repeat it. Things go at a slower pace so be prepared to wait at banks, stores, bars, restaurants and tourist offices. Waiters and bartenders generally don't work off tips, and while service is generally good here they also aren't bending over backwards to meet your every need. Yet I've never in my life seen people work harder or faster than they do in some of the bars and restaurants here when things are busy. As for working for tips from my point of view that's great. I can't think of anything I hate more than a waiter trying to find something to chat about when the time for the check nears. I'm here to eat, not to bond with the staff.