There are a lot of people better at fitting guards than I am, but I've learned a few tricks from those guys as well. I use a glued on paper template for the guard shape as well. Folded and cut, it's symmetrical that way. The guard is 1/4 mild steel left over from my grinder build. Waste not, want not.
Notice I center punched a row for drilling. The blade is 3/16, so I used a 5/32 drill. I don't have a mill, but Harvey Dean pointed me toward a way to make the guard fitting much easier, even without a mill. I envy Nick Wheeler's method of milling the slot oversized except for a thin area that contacts the blade. I can't be that precise without a mill, but I can use the same principle. After I drill my initial row of 5/32 holes, I run a 1/4 bit through the same holes, leaving about 1/32 of steel left at the bottom of the hole. Like Nick's way, it gives me less steel to file for the actual fitup. Here's a pic of the holes from the top, before I started filing.
I file the guard to fit fairly close, then I peen the face of the guard to roll the edges back in toward the guard slot. Then I drive the guard on for final fit. I used to struggle with how to hammer a guard on, till I found a piece of pipe and it all got much easier.
Here's the final guard fitup, before I clean up the face of the guard. Notice the peening I was talking about. Fitup is pretty good at this point.