The first thing I would do is go into the OC scanner and run that to get the score you should put into the clock setting. After you do that test to see if it's stable for a bit. Next you can increase the memory but I would go for smaller steps of like 200mhz at a time and see if it is able to run a couple benchmarks without any crashes or visual errors. You can even increase the clock but just a little bit since the scanner is probably pretty good at finding the safe max. If your going for manual you might want to just start at 50 for clock and then add 25 each test until it's unstable.
 
Biggest thing though is to start with the scanner to get an idea of what the card can do. Then test and continue to test often. Sometimes when overclocking it will run a benchmark just fine for the short benchmark runtime but when you load a game and are playing for a few hours things can become instable. That is why I recommend starting with an OC and over a few days consider increasing the number until it's unstable and you have to role back. Also keep in mind you have the 9 profiles you can store so it's easy to role back to the last stable overclock if you find errors.

Are you powering the card with two separate pci-e power cables instead of a single pci-e cable that splits into two 6+2's?

Thank you guys for the reply. I am powering the card with 2 separate cables.