Ask HN: How to get good at designing big and complex applications?

Hi HN! I am a grad student with a focus on CS, specifically Software Engineering. I like to explore different technologies that are used to build a product and am fascinated by the way people design such big complex systems. For instance, I am taking a class on Operating Systems right now which also requires me to develop my own kernel. I am finding it very exciting, challenging and fun. I would really like to know what all I can do to get better at designing such big complex systems. I try to read open source but it always feels like a challenge. I don't know if I have the aptitude for this but studying CS and the thought processes of people who have spent so much effort in this field gives me a lot of joy. So, if you have any advice, resources, books or tutorials that you think might help me, please do share. I would be really obliged. Thanks!