Ignore EVGA precision. Get MSI Afterburner. Its quite simple.
1. Increase the MHz slider by a smallish increment. Lets make it 100 MHz for the first bump.
2. Stress test with 3D mark 11 or Furmark or similar program. (keep a close eye on temps, you dont want to exceed 90C for now)
3. Up MHz by 50MHz until you error, reboot or get artifacts(line or blobs or strange shadows, that sort of thing)
4. After any of the above and your temps are still acceptable start increasing voltage.
WARNING : Once you increase voltage the risk of damaging is increased A LOT! Use sparingly and in VERY small increments, the smaller the better. I usually suggest 0.02v at a time...
After you increased voltage repeat 1 through 4 until you reach unacceptable temps or errors, drop one batch of MHz and V's, do a few more thorough stress tests and a game or 2. If all is well then VIOLA! You have your OC... But I would suggest you really not push your card as is, its plenty powerful as is.