You get issued a lot of stuff. If you're trying to keep the amount of stuff you bring minimal then I would recommend:
1. A leathermen
2. Duct tape
3. Zip-lock bags
4. Extra underwear
5. Extra socks
6. A debit/credit card
Beyond that, you'll be issued most of what you need. I would also recommend bringing at least one good set of civilian clothes. Ironically enough, there are a multitude of events and trips for which a plebe might be able to wear civilian clothes. That being said, a lot of plebes don't usually bring them to R-day and thus don't have any until after Thanksgiving break (unless they have clothes mailed).
That being said, you can't have a multitude of civilian clothes. I would recommend showing up in civilian clothes that are no too casual: IE a shirt with a collar and jeans. I would recommend showing up in the kind of clothes you'd wear if you were going to the movies with friends (with a collared shirt--it doesn't have to be a dress shirt).
Many people will tell you many things about what you should show up in. The reality is that everyone will go to a point shortly after showing up and having their hair cut where they will change into the same thing. So what you wear initially isn't really all that important. And by showing up in said clothes you can ensure that you have at least one pair of good civilian clothes.
What you bring really depends on you. For me personally, I don't rely on too much stuff so that's why those six things are things I'd recommend. You get issued a lot (including shoe shining materials) so you don't really need to bring anything with you. Theoretically you could show up naked and you'd be alright.