Thousands of hackers, cybersecurity experts, federal agents, and others will descend upon Las Vegas next week for what are always interesting conferences — with talks on as varied applications as hacking cars and airline boarding passes.

Two of the largest conferences in the hacking world will be happening — Black Hat USA and Def Con — along with a Darpa competition between autonomous computers right in the middle of both.

More than 20,000 people are likely to attend.

But what should you expect while you're there? Should a new attendee be worried about getting hacked? What talks are a must?

These questions and more were asked of some past attendees. Here's what they told us.