First Steps to Overclocking?

I want to overclock my pny gtx 650 2gb's core clock. I am new to this and I have no idea where to begin.

Do I use software to boost performance if so what program?

Is the temp of my GPU the only thing that tells me when I should stop or are there other things I need to look for?

Does my motherboard restrict me at all?

from your questions i would advise you to enjoy your card without the oc

untill you have done more serious research at least . why damage good hardware when you lack understanding. but if you must first find out if pny still offers life time  warranties and register your card online with pny 

As nick_Fury says then you should really do research before starting overclocking your card.

If you need software then I can recommend MSI Afteburner as a great overclocking utility and you properly want to get a good stress testing tool to see if your overclocking is stable, that could 3dmark or perhaps Furmark or so 

My advise is, start slow and don't burn off a good GPU because of not enough research.