What advice would you give to a first year CSE student?

Very beginning thing is to know/realize in which field you want to go i.e your interest.

Some Sub-fields of cse are-

AI(Artificial Intelligence), ML(Machine Learning), Web Development, Data Scientist, Cyber Security and many more.

All common in these fields is to learn programming.

Programming Languages may change for each filed.
All programming languages are same logically but different in syntax (words which you write).
Same concepts in all like if else,loops,class and objects etc.
So,Try to Learn basic languages if you want to begun (Like: Python, C, C++, Java)
Practice Daily for perfection in any programming language.
Solve Questions.
You can also learn it online because in B.Tech 2nd semester you will be taught programming.
Many online courses are there and you can also start learning on youtube.
Work on small projects and complete them.

Now Which programming language for which field.

AI,ML- Python is widely used.
Web Development-html,css,javascript,php,mysql (But now a days Nodejs is widely used) and many more.
Data Scientist-python and it’s frameworks.
Cyber Security-html,php,c++,c,python depends.

There are also other fields not mentioned here ,you can google them .
IOT has also good future.

Think any project in your field that no one has created. (Eg:-Like Mark Zuckerberg made Facebook that no one had done before). Think something different. Make strategies and work on your project will really help you a lot in future.
It will make you unique from others i.e You will have great expression in interview.
Any company wants those persons in their staff that can make profit to them and push forward there company… that guys those have productive mind…

I know this all seems not familiar to 1st year B.Tech student but you have to do hard work finally.