<p>Learning a language is a life long process, but sure I know what you mean.
Start with C++. It is in my op the best language to start with. You will learn about many important concepts that some other languages take care of (eg dynamic memory etc). It is important to understand these concepts. C++ is also very commonly used.
Also learn a scripting language. Python perl etc. Good to have C++ and a scripting lang. </p>
<p>If you really into numerical methods and analysis something like FORTRAN (old school huh) might be useful. You will learn matlab fairly easily after all this and its something you can easily pick up in school. </p>
<p>Theres a reason why so many school start their engineers with C++</p>