Here is what I do.

I found this site to be really good for seeing the ladies pics and prices and availability. Then I cross check them or their agency by phone number using TER advanced search function. That way, when I show up, I know that I have done my research and usually get a good result.

However, do not even think of picking up a street girl  on Ramblas street. Chances are you might get mugged, drugged, slugged or find it was formerly a boy or still is with makeup. Look but don't touch. There is also a nice nude beach to the north to check out. As well as the Dali exhibit and the churches.

Some things to do while in Barcelona, Spain; visit the Picasso Museum, Antoni Gaudi's unfinished church (La Sagrada Familia) among his other projects, walk up to Olympic Stadium on Montjuiic, visit "Snowflake" at the Barcelona zoo the only known white albino gorrila (I was there in the 80's so he may not still be there) and I would also suggest taking in a bull fight at Plaza del Toro Monumental but I believe they banned the practice back in 2010. I'm envious! The women are beautiful and the cuisine is great but bring lots of money because the shopping is world class! "Barcelona és bona si la bossa sona"!

Beware of Pickpockets!

Barcelona is indeed a great city, but it is also world class in aggressive pickpocets, especially in areas freqented by tourists, around hotels, currency change places, on the excellent subway, etc.  They often work in pairs, are fast, tricky, aggressive and brazen.  If you're going to be out in public, it's a good idea to carry a money belt.  Same is true of other Spanish cities, but Barcelona is the leader in that respect.