Antisthenes said:
However, is there perhaps more books, for newbies, about the general mindset necessary for being a good mathematician? Read "A Mind for Numbers" by Oakley, but it contained almost no examples of how to solve math problems in creative and different ways. Really need to learn flexibility when visualising and thinking mathematically, it seems.
Oversimplified we may say, that mathematics is a bit like playing LEGO, including the player's character. The textbooks can be compared with the accurate and detailed
models of all kinds, from castles to space ships. Doing mathematics is then the big box which contains
all kinds of bricks and you start building something without a detailed plan but a general idea of the result. Until then the structure is rebuilt many times, extended, changed and often a compromise due to the lack of optimal bricks. So the bigger your box is, i.e. the more deconstructed models are in it - the more textbooks you've read, the better you can build whatever you want to.
I would say: Grab an algebra book (van der Waerden as I quoted in post #11, if you like more text, or Serge Lang if you prefer more formulas, or a freely available version like in openstacks, cp. posts #2, #9 and the link there), then a book on calculus (usually people here recommend Spivak, but I don't know, since my elementary ones aren't in English, or which I like very much,
Hewitt, Stromberg, (in engl.) especially because it contains a large section about the
axiom of choice at the beginning, but gets very elaborated quickly, or again openstacks for free) and either read both of them or evaluate which kind of mathematics comes easier to you, because these are the main streams with different techniques.