Ask HN: How to Study Mathematics?

For context, I am a university student just finished my first year, studying mathematics and a mostly unrelated humanities subject. That said, general advice in the topic is probably welcome for other readers. I was drawn to mathematics from a young age; however, in recent years my attention has been taken by my other subject. That said, I don't regret taking the course at all and I enjoy it, although some topics I prefer to others.

My institution gives a very significant incentive to those who excel academically in their early years. I would beat myself up if I did not use the unique opportunity of vast free time this summer to advantage myself in this regard.

My question is essentially for those who have experience studying the subject at university level, or self-studying to an approximately equivalent degree, with emphasis on the pure and problem-solving end over the applied. What strategies, resources, and tips would you advise for learners?

Also, I understand that this type of question is asked fairly regularly. Due to the nature of this forum, much has been said about approaching applications of mathematics for those in other disciplines or for the purpose of self-study. But I think that most would agree that from the outset, pure mathematics and abstract problem skills appear arcane from university-level on.