This was the first Drupal Balkan Summit ever made. It was held in Novi Sad on October 8th and 9th, in 2011.
While there is not too much value in slides, the presentation was about possible options Drupal starter may have when it comes to appearance.
Still it is very debatable when it comes to the question "How to start theming in Drupal?" and that question is about to never be answered. As absolute answer is simply not possible, that doesn't mean that there cannot be some suggestions on current state along with use case scenarios.
That is exactly what about this talk was. Most importantly, it included discussion on best routes to take according to needs, knowledge and current state of themes in Drupal. That field alone is changing at blazing pace.