build it bigger than you think you need... my Garage is a 3 car garage (with a room built in at the back) which i will incorporate into the main garage this summer, we looked at 5 or 6 houses and i turned them all done due to Garage space essentially.. its amazing how much space you use when working on cars, especially with a project car ect, best advice would be to build a comfortable size to work around the car with the doors open, if i were home id wire it for you and give you best advice on what to go for power wise (and a keen price to wire it too ) , lighting is key, pay cheap pay twice, lots of natural light is good too, and some 5ft LED lights would be the best option also get your electrician to put in a Welding socket even if you dont think you will weld, its cheaper to do it in the building process rather than to add it later, hope it works out for you i found it as exiting to renovate the garage as it was to do the house .. maybe thats a man thing