It took me a while to figure out that you need to pick certain options to start or add to the tree because they aren't always available.
I think the solution is to close and open the menu repeatedly until I get something I want?
Anyway, I'm pretty sure it is easy to get a list of options of which none have nodes and block yourself really quickly.
Or maybe that is the game, to see how far you can get without blocking yourself? That would make sense too.