This means you to learn the techniques, and you need problem books, with solved examples, that you can work through on your own, or with a small group. This is absolutely critical. This includes both complex mathematical calculations as well as back-of-the-envelope calculations.
Moreover, while textbooks are great references, nothing replaces a good video lecture or presentation, that gets to the heart of the physical concepts without being overly technical. n And remember that physics is fundamentally an experimental science. It is not just advanced mathematics. Even if you yourself are not an experimentalist, you need to understand the basics.