Learning System Design - not just for interviews

System Design has been discussed multiple time here in blind in the context of interviews. I want to get upto speed - (not in hurry and not for the sake of interviews), about system design, cloud infrastructure and especially the open source apps/services. If I can learn it doing something hands on that’s even better. What’s the best approach and the resources? I have basic knowledge and high level context but want to get to the details. I don’t mind paid solutions/training either.