Job fairs mostly focus on entry level employment and in that regard can be terrific. That said, even middle managers can visit a job fair, give out a business card, make contact and make a good impression and then get a referral from a recruiter for a differnt division or department within the same company.
Practice, practice, practice.Make all your mistakes first with someone you know. Give them the tough questions you might anticipate and answer with honesty and courage. Keep practicing until you get comfortable with being able to admit there are things you just don't know. Gracious, humble people are an asset in the workforce.
Some jobs have fixed salaries with no wiggle room. Others would like to look that way, but they have some room to push the envelope. Find out in the first interview what the "range" is. Most importantly, don't answer the question in any direct way about what salary you will accept. If you get this question, say that you have a range, depending on a number of factors. Then throw the range question back at them.Don't get stuck in any salary negotiating until an offer is imminent.
The question always lurking in the background of every interview is Why Should I Hire You? To prepare yourself to answer that question, do as much homework on that employer as time allows. The answer is "I can meet your needs and deliver value to your (fill in the blank: company, department, processes, teams, products, bottom line, image, etc.)