I started with the HTML, CSS, PHP and SQL package and when it comes down to it, these languages are not going anywhere. When it comes to marketability, I think these four are a great jumping off point, as you can see preexisting solutions and then create your own versions of them, really getting to learn the way of the land and being able to create some amazing solutions. For example, I am creating an ergonomic health platform, and it is based using a heavily modified bootstrap theme, with PHP acting as my server side engine. Using that as a base I was able to learn how to serialize my data into a readable JSON to drive content into the iOS app I am developing to work with the system. Good luck! There are a lot of tutorials and resources for you to use, and you can even take open source software apart and see how it works for when you get more comfortable with reading the language.