Here is small tutorial in pictures of an idea you can easily adapt to your own clothes whether they are new or old. It is also cheap and easy :-)
First you need a piece of garment, I have chosen a new blouse I bought in Primark last week
Then you need studs, I have chosen pyramis studs for my blouse.
And a tool to close the studs. I don't like to spend money on thing I don't think I need. So my "tool" is a 10 pence coin :-)
Make sure you choose an item where the fabric isn't too hard or stiff as it will hurt your fingers (unless you have the proper tools). You want it to be a fun experience, right? I have freestyled my pimping, but you can also have a plan as to where to put the studs. Once you have decided on what to create, just pierce the fabric with the studs and close them with the coin or tool.
This is what my finish product looks like. I'm going to wear it tomorrow when I meet the girls in Stratford City, might match it with my faux leather skirt and I'll show you what it looks like in an outfit tomorrow.
Have fun ;-)