One thing you're going to hear over and over again is "it's all about who you know." As such, one of the biggest mistakes you can make is to be too afraid to use your contacts. If you know someone who works in your chosen field, even if you haven't spoken to them in years, send them an email asking if they know someone you can talk to. And then talk to that person. You'd be surprised how little it takes to get a job when you can open a conversation with, "Hi, respected_coworker_x recommended that I talk to you about a position in your department."

In short, don't let fear of awkwardness hold you back. Most people are happy to help you out, especially when it takes zero effort on their part. Use your contacts, don't be too picky (you can always specialize later), customize your resume for each position you apply for, and pursue as many opportunities as you can.