Many people says that in first year you have nothing to do just do fun but its not true the main Things you have to follow in hour first year are mentioned here step by step
learn any programming language between c++ or java.Learn it fully complete its basics and make it handy.
after learning a new language the most important topic is DSA- Data structures and algorithms. Start learning this don't do too first just learn it slowly step by step
Its the Roadmap till your first sem then
3)start learning some devolopement as web devolopement or android devolopement. My suggestion wil be start learning web devolopement and do it through out your first year make projects.
Note:-
When starting devolopement don't stop practicing DSA solve DSA based problem daily on competitive platform. At least solve 3- 5 problem daily. At the end be consistent.