Make a model . Invest in modeling clay or use cob, sticks, etc. Make sure of circulation, levels, doors and major openings before you begin digging. Realistically project yourself into the worst possible, longest, hardest rainstorm. Make sure water can flow away fast enough.
Heavy machinery wrecks the site, compacts soils, damages ecology.
Keep mechanized equipment under constant supervision. Better yet, keep it off the site altogether. Too big . Start your first building tiny to make sure you can finish the first season. You can add on later.