The first thing I did was remove the paint around the rust. I used a 4 1/2" grinder with a 120 grit 3M Sandblaster wheel. It worked really well for taking off the thick layers of primer and paint. I carefully worked my way around the rust spots and removed paint until I could see clean metal surrounding the rust.
I also used that wheel for removing all of the light rust that hadn't pitted the metal.
Note: Before grinding, cover up anything that you don't want to get dusty. The paint dust is super fine and covers everything. I had my hood open to help access some rust, so I got a tarp to cover up the engine. Having your windows rolled down here would be a bad idea.