The Joys Of DIY Home Renovations
This video in a basic beginners guide to DIY drywall.
They are not showing techniques the pros use to put up drywall fast.
First off in most parts of the country you would need a better vapor barrier that what they are using. Check your local codes to see what is required
For most drywall jobs you start with the ceiling then you push the sheet on the wall up tight to it.
Gaps near the floor will be covered by the baseboard. You want the gaps between sheets, that are going to be taped, to be reasonably tight (1/8 to 1/4 ” is OK)
Watch the video to discover some more great beginner tips.