My advice is an will always be. Do what you can with what you got. If you set up a few different ways to heat your garage you can switch between whichever is most efficent and safe for whatever you are working on. I have radiant heat, kerosene heater, infared lamps, and a couple of space heaters. If I was building a shop or did not have any heat set up yet I would consult Dave (there is no substitute for knowledge from someone who does something for a living)

My advice is to have at least two different ways to heat your garage.