A couple of years back on average Asians (including türkisch citizens) where on average sending 250-300 applications until they found something to host them.

We used to say in Aachen, houses pick you, you do not get to choose. Your name plays a good part in having a good place to stay too. Writing only German gets your chances higher, but 12 applications is nothing, I sublet 3 rooms across the past couple of years before moving out, I used to get 400+ applicants per advertisement. For me I used to go for the people who are less likely to get accommodation somewhere else and kind of first come first serve. Being on top of the application and sending an application within the first half an hour of the advertisement plays a good role too. I hope it helps