It is always advisable to start early, You can start by doing certification courses in various domains which interests you from a reputed institute like codingblocks or a certified websites like Coursera,Udemy,edx.
You can also pursue specializations in the domains such as :- Marketing, Search Engine Optimization,Web-development(HTML5,CSS), Internet of Things,Embedded systems, App development (Ios and anroid) or if coding is what your interest lies, then you can learn programming languages like C ,C++,Python,Java,Ruby. Having a strong foundation of programming languages is crucial for any CS student because, this is what your stream comprise heavily of.
Certification courses not only enhance your technical knowledge but, are great value additions to your CV because Companies today hire people with vast knowledge of different domains.
In addition to this, you should also do internships in all kind of fields and start developing practical projects .