I guess if I had any advice to offer to someone heading off to
college, it would be to take advantage of an amazing opportunity.
Meet as many people as you can (faculty as well as students, and
people who are not just like you). Do the work, but also find
time to play. Explore areas and topics and courses that are
different from things you know well -- don't just repeat high
school. Listen to advice from everyone (including parents and
well-meaning others) but make up your own mind about what to do;
it's your life, not theirs. Do things that you like and find
interesting; don't worry about making a lot of money. And so
on -- lots of platitudes. Mainly, make the most of it.

I have often suggested a talk that was given by my friend and
mentor Richard Hamming, inventor of error-correcting codes among
other things. Your mileage (and your brother's) might well vary,
but it's worth a read. You can also find video versions but I
like the text, since it was the first time:

https://www.cs.virginia.edu/~robins/YouAndYourResearch.pdf

There's good advice in there.

Best to you both.

Brian Kernighan