Expect to be very, VERY tired at the end of your one day.
There's a web site somewhere (I think you can probably find it through -- or on -- the NSSF web site) that shows the layout and lists the exhibitors. You can use that to decide what booths you want to visit, and to plot an efficient route through the show.
Rumor has it that roller skates are useful there.
Having been to some really large trade shows, it's best to make a plan of what you are interested in.
And head for those first, with other wanderings left for later.