My advice would be if you have access to the syllabus before you start your class read it over so you know what to expect.
A notebook & pens & stuff would be fine, and I agree with everyone who said don't buy the book before you start th class, because you never know, and i know my university is really strict on returns. (once i bought a book for 80$ and only got 20$ back for it because it was "out of the package")
And if you can get 2nd hand books they're great, much cheaper, and sometimes there are important things highlighted/written down in them.
Don't be nervous, and dont be too worried about making friends right away, in college/university there's alot more focus on academics than socializing, i didn't have any friends until about 3 months in!! haha
If it's in a big lecture hall, make sure you pick a seat where you're comfortable and will be able to see/hear everything well (and if you're easily annoyed stay away from groups of chatty girls, because they WILL talk through the whole lecture, trust me, I know hahaha)
And ifposible I'd try to get there at least 15-20 minutes early so you can get a good seat and get comfortable and organzied before the lecture/class begins.
That's about all I have for advice, any more questions feel free to ask.