Great advice above, especially about stopping to think when something isn't clear or you're tired.
Treating yourself to the right tool rather than the "about right" tool can make some jobs a lot easier.
Check the packs in enough time to get the missing bits delivered by when you need them.
Good lighting underneath.
Carpet the floor (or something posher to taste)
Test run bolts through threads before assembling on the car.
And (without reopening any of the other sort of threads): protect your eyes, disconnect the battery when you play with the electrics, and have the right sort of fire extinguisher in the right place.
Enjoy the build
Jonathan
PS: Whereabouts are you?