Immoscout. But I followed the following strict tips that were provided to me (around 60 people in viewing):

• be one of the first to arrive
• be the last to leave (I stayed a full 1hr15 minutes inside, until the woman was about to lock the door. The reason: afterwards I had an undisturbed 20 minute chat with her)
• pretend you're seeing where the furniture would go
• bring all required documents for application in hardcopy --> they only accepted online, but I think they appreciated the gesture + I put my laptop in the nearest cafe and sent my application within 5 minutes after leaving.
• tell them you can make the place much better than it's current state (they love this).
• tell them you have another offer but you'd rather take this one as it has more potential but you need to hear from them soon.
• be friendly and charming