data science / machine learning resources?
Start with the Coursera's Machine Learning course. It does a really good job in introducing the student to the domain of Machine Learning and helps you lay a solid foundation in the concepts.

In case, you feel that the math is a bit dumbed down in that course, you can take this course, taught by the same professor and is more math-intensive than the former.

Now, you would have a clear intuition about the basic concepts of Machine Learning. Take this course, which can be said as a follow-up or a supplement to the course of Andrew Ng.

This resource from IAPR has in-depth notes on a lot of ML concepts like cross-validation, regularization, etc.

You can also have a look at these amazing list of resources compiled into a blog on Quora.

Now, for diving into advanced concepts of neural networks and deep learning, you can make use of this free book.

Finally, the free e-book: Elements of Statistical Learning is a wonderful book for beginners in ML or Statistical Learning.