Simply line up your chisel along the line you are going to cut and strike the back of it with a hammer.
Cutting 22 gauge sheet metal.
Straight shears and throatless shears.
Additionally the type of metal you are cutting make a big difference.
If it can handle 18 gauge steel it might be able to handle 22 gauge stainless and that is a big maybe.
You can go up a couple thickness with aluminum 20 gauge steel vs.
A soft wood backer will allow for the chisel to pass through more easily by providing support for the metal.
Use a bench shear to easily cut most gauges of sheet metal.
Bench shears come in two general types.
If your project requires cutting a hole in the center of sheet metal draw it on the metal as you would any other cut line.
Straight shears make cuts that are straight lines.
18 gauge aluminum but the opposite is true for stainless.
Then create a pilot hole within the penciled circle using a power drill.