I work at a university career center, so here's my US$0.02:
- Call the career center and talk to the person running the career fair. They'll be the best resource for you and just as badly as you want to find a good student, they want their students to get hired by you.
- BE NICE. Seriously. To everyone. Arrogance and/or plain rudeness doesn't get you anywhere. Don't expect to be treated like royalty just because you're "with the #3 bla bla bla". If you get on people's good side, good things happen.
- Get a good, clear display. I've seen all sorts of displays at our fairs. The photo board that's a mish-mash and the 10 stacks of plain-paper flyers. Focus in on a few nicely done brochures/handouts, and a big clear display. The less garbage the students have to filter through, the easier it will be to find the talented ones.
- Know what kind of candidates you're looking for and make your materials address that.
- STAND IN FRONT OF YOUR TABLE. That way you look actively engaged in talking with students, not passively sitting back and waiting for them to come to you.
- Do NOT stand in front of other companies' tables. Again, be nice. If you get a lot of students coming to see you, ask the fair organizer for some help. If you were nice to the organizer from the get-go, they'll come help you out in turn.
- Hold events on the campus prior to the fair. Take out ads in the school newspaper. Give talks to student groups. Get known.
- Offer internships. PAY YOUR INTERNS. You might not know this, but Federal law says either the employer has to pay the intern or the intern has to take a class. That means if you're not paying them, not only are you getting free labor, but the student has to pay to take a class, so in effect, they have to pay you to work for you. That's not Nice.
That's not an all-inclusive list, and it's certainly not universal (all depends on the school's approach to running the fair). Some of it is probably obvious, but I hope it helps.