Go early and wear plety of sunscreen. I recommend two shows - I assume they'll be there again as they've been there the past two years.
Tom Knapp's Shotgun Show. You don't have to be a gun lover or a hunter to appreciate the skill this man has. And there is crowd participation.
The birds of prey show. That isn't the real name, but you'll find it. I don't think the show I saw this last time was as impressive as the year before, but even so, it was totally awesome. Take your camera to this one.
Both shows are an hour.
If that ain't your bag, the rest of the Expo covers everything that
TPWD does. All sorts of demos things to do - guns, archery, fishing, dogs, lots of stuff for free and to be sold.