Couldn't find your other thread (must have been deleted) so I'll answer here.
Personally I use MSI Afterburner, but have used PrecisionX before. Both are simple to use.
Start by increasing the Core clock by 10-15 and benchmark each time you step up. You can either play a game or use Unigine Valley. Watch your temperature!
Then move to the memory. This will produce artifacts as soon as it's raised too high. I recommend increasing memory by 5 until you've gone high enough d it's stable.