HD Radeon 5750

I wanted to overclock this, how should I proceed it?
The GPU tends to get hotter than all my other parts so should I still be overclocking it?

Is normal that GPU's run hotter then all other components. You can improve the cooling by manually increasing the fan speed, but noise can become an issue.
Try MSI Afterburner for both OC and the fan speed.

Could you guide me as to how to use it to overclock? I've never oc'd my GPU before

Not quite sure on that particular GPU but; do 25MHz increments on the core till you find the max without having to increase the voltage and/or till you hit your thermal limit, then do the same for the memory.
MSI Afterburner comes with Kombustor that will let you to the stability test on your OC.