Keep your ticket until you leave the train stations, Keep your belongings safe from pickpockets, and use the metro as frequently as possible to save money.
Explore offbeat sites like Sant Pau, Try to get skip-the-line tickets wherever available, Don’t try to cover all the attractions in one or two days.
If you’re going for the first time, try staying close to the main attractions, Consider living in an Airbnb, Book your accommodation in advance for better prices.
Entry to most major museums is free on the first Sunday of the month, Take public transport instead of Taxis.
Avoid talking to random people who approach you asking if you speak English, Avoid the unsafe and non family friendly areas.
Plan your itinerary practically to avoid getting overwhelmed and spending too much time at one place, Learn some common Catalan phrases, Pack comfortable shoes, Barcelona is full of walking.
When traveling for the first time, don’t be afraid to ask for help, the locals are generally very helpful. Make sure to soak in the history and beauty of the museums, monuments, food and other localities. All in all, make the most out of your visit and you’ll not leave disappointed.
Though not considered rude, you're not required to leave a tip in Barcelona. Most people don't tip or usually round-off the bill amount.