The multiplier is just that, it multiplies the baseclock. So if your baseclock is 100 and your multiplier is 10, you'd be at 1000 mhz. If your multiplier is 20 you're at 2000 mhz. I'd raise your multiplier to 20, but that's just me... typically easier to overclock off of the multiplier than raising baseclock. Linx and prime95 will USUALLY reveal instability, but not ALWAYS. If it's stable in prime95 and linx it's typically going to be a stable system.
There's several voltages you need to take note of and optimize depending on what you're doing (pll, vcore, etc.). If you're raising baseclock you also need to take consideration in regards to your memory multiplier and the type of memory you have. Tom's has done a decent article in the past on overclocking an i5. I'd read that