I've posted elsewhere on another cock ring thread. Start off with some rubber/silicone rings. Try 1.125" behind the glans, 1.25" on the shaft and 2" around both the penis and scrotum. Once you're sure how they fit and go on and how easy it is for them to come off, you could move to metal. I have a variety of designs and widths in silicone, aluminum and stainless steel, in silver, red, and black. Look at your local hardware store for stainless steel "harness" rings. Around me, I can find stainless steel rings in 1.25", 1.5" and 2". One inch rings are common for behind the glans, but try the larger 1.125" first.
