Safest way to overclock is to just bump the multiplier in the bios slowly until you hit the limit or whatever speed you're going for. Avoid touching voltages if possible. The stock fx8350 multiplier should be x20, and i believe the multiplier bumps by .5 increments.
Overclocking limits are determined by your CPU cooler, the motherboard, and the CPU itself. The cooler is pretty much the thermal limits. if its past safe temperatures, you'll know because you'll be blue screening or your PC might shut off as a safe measure. Your motherboard determines your limit through the number of chokes it has. The chokes basically just are power phases for your CPU, the more the better. The last part is the CPU, which can be random. It's all luck, some can overclock higher than others. If you get a good one, you might just be able to overclock it to high speeds without having to worry about voltages.
Your motherboard itself doesn't seem like it'll hold a heavy overclock from what I see, of course I could be wrong. I would just maybe try having the CPU run at 4.3 or something, if it's not stable, back off to 4.2.
Test the overclock with something like prime95, intel burn test, or OCCT, and monitor the temps with HWMonitor, or CoreTemp or kind of program like that.