Asking for a raise
mbrubeck: The biggest thing you can do to improve your chances is to look for work elsewhere.  If someone else will pay more for the same work, then you have an obvious bargaining point at your current job.  And frankly, it's much more likely that you'll get a significant raise by changing companies.  You current employer probably doesn't have another 100-200% of your salary just lying around in a budget somewhere.