Dress for Success. Treat this like an interview. If you do not have professional clothes to wear, come to Mellencamp 128 and get some for free from the Career Closet.
Introduce Yourself. When you walk up to a recruiter, smile, firmly shake their hand, establish eye contact, and give your elevator speech (a brief 30 second introduction about your education, interests, skills, and why you are interested in that company).
Bring Copies of Your Resume. Some employers may ask you to apply online, but having a paper copy to hand them can be helpful.
*BONUS TIP*: Get your resume reviewed at walk-in hours
Research Companies/Organizations Before. Know the basics about the company before you meet with them (what they do, what they are hiring for, etc.)
Source:- https://uwm.edu/careerplan/students-2/jobs-internships/career-fairs/