I know it's popular on car forums to say "It's never big enough", but it can, in fact, be big enough (or too big). Think seriously and realistically about what you are really, really going to do with the space. Be honest. Are you going to have ten cars? No, probably not. They're a PITA to maintain, cost a bunch to buy, insure, and maintain, and you're not going to use them all anyway. More space = more heat and cooling. Maybe only part of it needs to be tall enough for a lift. Maybe you don't need a lift, even though the entire internet says you do. Do you have kids? If you're planning to, plan also to spend not much time in your shop. I built my 30x40 before kids, and then had a half empty, seldom used garage for 10 years.
On the other hand, I learned that 10' of width per car isn't enough. I'll go with 12' next time. And yes, add lots of outlets, but you'll only need two per box if they're close enough together. I also ran cable for 220V, which I haven't used yet, but I'm glad it's there. And I set up the 110V outlets so that there is a different circuit every other outlet, 6' apart and 4' up. I had the contractor put in a rough-in for a bathroom...that I never finished, but it's there.
White paint makes the space much brighter. Think about where the windows should be, and if you want any. I ended up with an 8' wide door where I expected a 9' wide door. I didn't expect that because I didn't understand how much width had to be "not a door".
I recently read that stick-built is stronger than pole buildings, but I'll defer to the posters on here that actually know for sure. In any case, think about how much you value what you're going to put in this building, and select construction style accordingly.
Think about the distance between the house and the shop. How do you feel about walking out ot the shop in cold, rain, and snow. How will you feel about it when you're 60 (hint: not the way you feel about it now). On the other hand, don't make my mistake and leave insufficient space between the house, garage, and property line to hide a car or 3 behind the garage.
My next garage will be insulated up into the "You really don't need to do that." range, so I recommend that you plan the construction details to support lots of insulation, including the floor as noted earlier. It may be a bit smaller (yes, smaller!) too, like 36x30, and have a covered outdoor work space with a stainless table, power and water nearby.