• Begin your visit with one of the "hop on, hop off" open-air buses that depart from Catalunya Square, then stop and go regularly at many of the city's top attractions (there are a few companies that offer them, with ticket booths in the square). Go for the seats on top; wait for another bus if you have to. Viewing the exterior of Gaudi's masterpieces from this vantage point is the perfect introduction, and also gets you oriented to what's where beyond the city center.
• For Sagrada Familia, which almost always has long lines, buy tickets in advance at one of the many automated ticket booths marked "Caixa" situated around the city. For info on how to order and print time-specific tickets, go to www.startribune.com/a1818 and scroll down to the entry on the church (the site has advice on money-saving pass cards for multiple attractions). You will be ushered in almost immediately at the designated time. Consider taking the elevator down as well as up, especially if it's hot; the extremely narrow circular stairways can induce faintness and nausea.
• Pay a bit more for the self-guided tour headphones, available upon entrance at Sagrada and the houses, even if it's not usually your thing. The extra background and explanation of architectural details are worth it.