First you need big tools, huge ones, the famous brandnames, like Mikita, DeWalt and of course some Leatherman scullery!
And a Jim who'll help you fix it, with lots of concrete. And some laser precision measurement tools. Also a tool belt, that rocks!
But first put some gravel in them holes for the posts. (At least I saw them do that on JooTjoop, for some water thing reason.)
Never tried to build a deck, seems like a tricky job. Good that you have kind a handy neighbor. It's gonna be a great deck I bet.
He has a laser spirit level!! It's like something out of Ghostbusters!! I have a yellow battered metal thing. You are right about the gravel, he has been quite cavalier with what he piles in, gravel and dirt then the 'crete. At the risk of sounding pathetic all his tools are fucking massive compared to mine. As is for real work! Don't know of or will get done for the weekend but it's looking good so far!
Those real powertools are already half the job, but they also cost an arm and a leg. (As a figure of speech, not due to wrong appliance.)
Thumbs up for getting the job done before the weekend! Cheers!