Hello,
What is your motherboard? Fortunately, you have an Ivy Bridge CPU. If it was Haswell, since you don't have an unlocked CPU, it would of been more or less not possible to achieve a worth while overclock. With Ivy Bridge you have a limited amount of overclock you can do, which I would think is worth while. Probably rather easy to do also.
What CPU cooler do you have? Basically any decent after market cooler will do. The Intel cooler wouldn't be able to get much.