Barcelona has quite a large and a very easy-to-use transportation system. After the 1992 Olympic Games that were held in the city, municipality has largely improved and upgraded the transportation system. It is not difficult to get around city without spending a huge amount of money.
You can use Metro which happens to be the easiest and fastest way of getting around Barcelona. All you need to do is, find out the station name for each end of the metro line that you're planning to use. This will help you in understanding direction which you must stay even if you do not understand a single word of Catalan. It is recommended that you do not buy metro tickets individually, buy them in strips. You can also buy passes which offers unlimited travel on both metro and bus networks and you can get to purchase these passes either from the station offices or from the automatic machines that are present at the entrance of metro station.
You must prefer to buy those tickets that include funicular and cable car lines. These tickets will be useful in case you plan to visit Tibidabo or Montjuic. If you prefer to travel on the road and see some of the city buildings as well, use bus service. It can be a bit slower than the metro system but it is certainly more eye-catchy. The buses and Barcelona are color-coded, while the red buses are restricted to stay within the city center, others will also take you out in surrounding areas and suburbs.
For short distance, prefer covering the distance walking, especially if it is the old Barri Gotic area and Las Ramblas. Barcelona has been very well designed for traffic and you also get a chance to see some extraordinary architecture and experience the leisurely pace of the city. Make sure that your wear comfortable shoes so that in work comfortably. Some of the older parts in city have cobbled streets and rough areas so comfortable shoes will keep you relaxed.
Make your mind before renting a car in Barcelona. Most of the times, you'll have to leave your car in the parking lot which also comes at a premium since Barcelona receives heavy traffic and the parking area is a little less. Using public transportation system in Barcelona is the best and easiest method that you can enjoy the city. It is important that you be aware of the pick pockets in the subway system and do not encounter unnecessary problems.