If you've received emails and attachments or Links from unkonw persons don't click on those links or furnish your personnel details in return back emails.
Just checkout those sites on typing address bar for genuineness.
Mostly you should take care of short urls (Links). Most of the hackers making frauds with help of Micro blogging services.
Checkout once before clicking on that perticular short urls, just preview those short url site then decide to click on that urls.
By using special filters these spam links can be blocked.