Advice on re-roofing a house

Have the iron sheeting, have the man power. surely it cant be that hard?
I know there would be some DIY-ers who have done it themselves before without having to fork out about $10k.
Any tips please?

It is not hard fitting the roofing, tidy detailing is the tricky bit. Work your laps away from the prevailing wind direction. Mark where the purlins are on each sheet as you go, if zincalume, dont use a pencil on it. I prefer to lap each new sheet under the previous one to help keep things steadier, so organise your laps accordingly.
Make sure the guy on the ground passes each sheet up the same way, it is a lot easier to turn a sheet around on the ground.
Check for parallel from the far end every few sheets once a few are down.
Check the bottom overhang on the edge of every sheet to avoid runout.

Dont screw to the top purlin, you will have to leave room for the ridging later.
Leave an accurate mark below where the top purlin is so you can measure from it to fit the ridging.
Using a roofing spike to start makes screwing easier on the laps.
Start on the least visible side so you can get the hang of it before doing the more visible bits.
I found three people was right for the job, two on the roof, one passing up.
BE CAREFUL!

Don't get cheap one piece nails. For slightly more cost I got nails with a separate metal and plastic washer. It's really easy to remove those nails later if necessary.

LBP

Don't use nails (EVER). If you are using mates to help, then edge protection is mandatory even if they are volunteering.
Why don't you just get it done professionally? it doesn't cost that much.
Edit, Haha I'm a roofer and just noticed that live in your town .

Replaced a few sheets and flashings ridge/barge due to rust and lifted all the nails out and replaced them with screws. Got my cousin who is a roofer so it was us two. Worst part was lifting the nails if you're not used to doing it. was feeling it in the back afterwards.