It is a good idea to become familiar with the structure of a few different kinds of languages, as well as focusing on logic and critical thinking skills that could be applied to any language, such as learned to flowchart or create software architecture diagrams. Then you can apply these skills in any language you need to use.
Great question !
I am a subscriber of Medium.com, a website which has articles on almost every subject out there. In a day-to-day job, there might be some requirement that comes up that may not be fulfilled by your existing set of tools, so you’ll have to go off and find a solution.
Once you start working in a role, sometimes your knowledge might not be sufficient and you’ll have to go out and find what works. The problem is the mother of knowledge in this case. If I come across an obstacle, the first thing I do is ask around in my team. I’m lucky to work with brilliant people. If not, you can always use Google; we’re lucky enough to live in an era where knowledge is so abundant.
In this field, you’re always working on a deadline and you have to find the fastest solution — it might not be the best but it will be fast.
I also suggest you find an industry that truly interests you. Programming is a tool to solve problems. Once you've established yourself in the field as a software developer, you'll be exposed to new languages as needs change within that industry.
If, down the road, you want to move into management, solid technical and domain expertise provide a great foundation. And don't forget your soft skills! The ability to communicate effectively, both written and verbal, are key attributes of successful people.