Later this year (in August) the world's prominent classical music lovers will converge in a sleepy little Bavarian town for the annual Bayreuth Festival.
Source: By Rico Neitzel - http://www.rizi-online.de, CC BY-SA 2.5, https://commons.wikimedia.org/w/index.php?curid=976810
Most of the visitors to Bayreuth will have a ticket for one or more of the performances.
But the attraction of attending a performance is so strong that hundreds, if not thousands, of young travellers will arrive without a ticket and without the money to purchase one. These travellers will include young students and Wagner disciples from such diverse locales as Brazil, Japan, China, Africa, and America who have travelled to the festival on little more than a prayer. Instead, they are hoping to be "blessed" with a free ticket handed out by the festival's "Blue Maidens".
The "Blue Girls" („Blaue Mädchen“) are local men and women who are hired by the festival to act as ushers and assistants. The Wikipedia description roughly translates to...
The "Blue Girl" is a phenomenon of the Festival House in Bayreuth. The name originates from the traditional to 2008 blue color of their uniforms. However, since the festival summer 2009, they are uniformly dressed in gray.
In earlier times there were preferably unmarried young ladies from the vicinity of Bayreuth, but now the dominant workers are students of theater and opera-related courses in Bayreuth, Germany, Europe and the world. You have the opportunity to look at nearly all 30 performances a festival season of the Richard Wagner Festival in their service and to listen. From the season 2015 are also the first male "Blue Girl" in use
The acoustics of the theatre are legendary and so precise that every seat must be filled in order to maximize the quality of the performance. And the responsibility for this falls upon the "Blue Girls". So shortly before the curtain rises, they look for empty seats and then go outside to select one of the lucky travellers (this is what provides the motivation for them to get Bayreuth -- the chance of attending a performance).
A traveller/backpacker from, say Brazil, has come to Germany solely for the chance of being selected by a "Blue Girl" to fill an empty seat.
Question: how can their chances of success be maximized?
It's not attire because I have seen a bearded grungy backpacker from America get selected. It's not height or race because I have seen a petite Japanese girl swoon with joy when she was approached by a "Blue Girl". It's also not near the stage entrance because I have seen the "Blue Girls" select someone as far away as Cosima's statue (about halfway down the hill).
Source: Bayreuth - Grüner Hügel - Richard Wagner Park - Cosima Wagner Statue 1979 by Arno Breker
Note: If it is a totally random event and nothing can be done to improve one's chances, please put that as an answer because it's worth knowing that also. Also, substantiated attestations from a current or former "Blue Girl" will be highly valued.
Note: the odds of an empty seat at a Festival performance are massively infinitesimal and this question assumes the unlikely event that there is an empty seat in the first instance. Of the 30 performances each year, there are likely to be about 2 or 3 performances with one or more empty seats to fill. In some seasons there are none.
Note: there's a great video (German soundtrack, but German proficiency is not needed in order to get the gist of it) showing the 'blue girls' in action along with backstage interviews at The Blue Girls on the Green Hill.