Lots of fake websites
Lots of bad backdoored programs and e-mail fishing scams
If you visit a website check the address to make absolutely sure your on the real website.
Trust no one!
Lots of hackers are spreading nowadays because they knew it that there is big money in bitcoin. Be careful on what you're joining with if you know that is a hack don't take a risk to enter or access it or else you will be hacked.