Cards are really safe and easy to oc nowadays. U can turn everything up to max except core and men clock and nothing will happen.
Volts to max
Target temp to max
Target power to max
Core clock + 200
Set your own fan curve
Run a stress test like unigin heaven or just start playing a game. If it crashes dial it down 10mhz and try again.
Then do the same with the memory clock but u can start that value with +500. Dial down 25 at a time until stable.