Where are you located. May make a difference in construction.
Check out local planning and zoning ordinances FIRST, check codes for allowed sq.ft, set-backs, etc.
Determine what you want to use the building for. Simple storage, or finished interior for heated shop, for example.
Determine building dimensions.........then make it BIGGER. I wish I had 8 ft. more length.

Was in my plan , then chickened out to save money. Big mistake. I'm happy with it as-is, but would have been much nicer.
My shed is 3 yrs. old, 36 ft wide, 48 ft. long, 14ft. sidewall( Allows for 12 ft. overhead door for motorhome.
What is the snow load in your area.. Very important to have roof strength.
Check out a number of builders. Go visit structures they have built.
Put a rear overhead side door to get items out of the back w/o moving everything in front. Like mower, ATV, small trailer, etc.