Programming

Programming is extremely important in almost every area of physics. Not every physicist has to be an expert programmer, but at some point during an education in physics, you will be exposed to some amount of programming. In most experiments, the process of data analysis is complex enough to require some programming.

The best language/programs depends on field, but some smattering of C++, R and Python are a good place to start. As well as checking out the books I just linked, online courses are a great alternative. Code Academy is a great website which allows you to learn programming languages for free.