What do I have to pay attention to?

Hello everyone, I have read through the forum a little bit here, especially on the topic of financing and I have come across many helpful hints and contributions that have considered points that I myself did not have so much on the screen. Because I am also faced with the decision, in which mobile underlay I want to “invest” in shortly, I would be happy if one or the other also has tips for me. To my situation: I have a safe job of me etw a 2700 net. After deduction of fixed and own maintenance costs remain in about 1000 (paid are then in addition to insurance, also the purchase of food, petrol, “pocket money” for the daily small things, etc.). I saved about 15T and search with these key figures a car. To the requirements: Since the tastes are very different, I do not want to do here a model search in the narrow sense. I am looking for a car that is suitable for the future with regard to family planning, so that it may be a “little bit more” (size) for which the 15T should not be sufficient. Because I want to buy my first “real” car, I am already interested in new models and do not dislike financing. However, I lack any feeling about what size I can look around. What is reasonable? What is feasible? That you usually get great cars for more money is unfortunately a not to be denied context… Looking forward to your ideas, tips and experiences.