each room on it's own breaker, if not more than one.
more 220 than you think - - 2 for the garage
extra outlets
extra cat 6 runs for security
tall garage if you want to put a car lift in

The "say" it takes about building 3 homes before you sort of know what you want

go funky - get a monolithic dome

If you thinking about an "out building"; add extra service to your place to make sure there is room to grow.

Never ever plant trees or shrubs by the sewer lines.

Big pantry to store food, ammo, etc. extra big return lines for gray water.

safe room for weather events..