Solo travel Slovenia or the area

I’m 18M, and I’ve solo travelled to a few places. Now I’m planning to solo travel Slovenia and the countries around it. Tbh, my Eastern/Central Europe geography is not the best, so I’m completely lost on how to plan this. My plan is to book a one way flight to Slovenia and see where I end up because that’s what I usually do. I would have around 12 days, and I really like hikes and nature. I don’t enjoy partying at all. Any suggestions on what to do? Should I go to countries up north, or do I go south? Or is even choosing Slovenia as the first country to land a good idea? I’m completely flexible, and I’m just looking for a great place to meet people with beautiful mountains, lakes, and just nature.