So typically the goal is to achieve max clock speed within reasonable temps. So your core temp under full load will determine where you end up.
How to get there:
First, try to find Prime 95 v266. That's the last version that doesn't over-volt your CPU during stress testing. I'll typically use prime while testing OCs, then once that's stable run something like Asus ROG realbench for 8 hours to test long term stability.
If you're stable under prime 95 for say 30 minutes, and your temps are good, boot in to the BIOS and leave your voltage at 1.29 and increase core clock to 4.5, then run prime 95 again for 30 minutes. If stable again keep increasing your clock by .1 until you bluescreen/crash under prime 95. Sticking to the same voltage you shouldn't see temps rocket up as you increase clock. Its voltage increase that will add more heat.
Once you bluescreen, ASSUMING YOUR TEMPS ARE STILL GOOD, increase your voltage by .02 (so to 1.31 to start) but leave your clock at the setting it was at when you bluescreened. The idea is to feed your CPU the amount of voltage it needs to achieve that clock with stability. Back to windows and run Prime 95 again. If it bluescreens again, increase your voltage to 1.33 and stress test again. KEEP WATCHING TEMPS.
Basically keep doing this until you hit your target clock speed OR you hit max temps. Again, personally I'm OK with Prime95 pushing my temp to "maybe" 80 under stress testing but preferably high 70s. At that point under real world load apps may get it to 70 if they're VERY CPU intensive but it shouldn't be for long. In regards to voltage, I wouldn't go any higher than 1.35 personally. In fact I've never pushed a chip further than 1.32 for a full time OC. I like to keep it under 1.3 if possible.
I suggest google-ing around to see what max clock speeds others with your same CPU are achieving, at what temps and at what voltage especially. Every CPU is different and all motherboards are different so you may not hit what some others are hitting. All depends on your cooling too.
That's the 101