Ask HN: How to tackle Computer Science?

Hello HN,

I just finished a year of college, my majors being Computer Science and Pure Mathematics. I joined college with no programming background and little mathematics under my belt and although I breezed through the introductory programming classes, I realized that to be a good Computer Scientist, I need to know my theory really well and of course my mathematics.

Next year I will be having a semester that will cover Algorithms and Data Structures, Parallel programming in Java. The other semester will cover mobile development.

So, now my problem is, I'm not sure where to start learning more advanced CS stuff on my own. Where do I start with learning algorithms on my own and how does one know which algorithm to use and when? I want to self-learn machine learning as well(since it's not provided in my college) but I'm not sure what mathematical and computer science background I should have before diving into it.

Finally I would really appreciate if someone could give me a rough guideline of a typical CS learning ladder, including some books which could help.

Thanks HN.