A wind tunnel is a super way to try out free fall before you go on to the real thing by jumping from an aeroplane. Discovering that you have control in a wind tunnel, and can fall in a good stable arch is an excellent confidence-builder. It will also most likely give you a fair idea of whether you will like skydiving as a sport. It's also immense fun! Most people love it – if you don't like it, then quite possibly, skydiving isn't for you.
You'll be grouped with some other first time flyers and briefed in a classroom together. Most likely the briefing will be about 20-30 minutes, then they will equip you with jumpsuit, helmet, goggles, and make sure you remove jewelry and tie hair back before preparing to go in the tunnel itself. It varies around the world but most wind tunnels have a chamber (for flying in) and an ante-chamber (for waiting to go in when it's your turn). Once you enter the ante-chamber a pressurised door will seal behind you, and you won't be able leave until the whole session is over. So make sure you take in everything you might need, such as a bottle of water, lip salve, tissues.
Relax, smile and enjoy flying! If you have never flown in a tunnel before just go with the flow and follow the instructions you are given. But still, make it clear to the coaches that you want to learn to fly your body in the air, not just do the fairground ride thing. But don't expect too much. It would be impressive if you can fly in a stable, relaxed position without being held. If that's going well the next stage is 360 turns, stopping again on the same heading.
Location is the biggest factor. See what wind tunnels are closest to you, check their websites and see which appeals. Book whichever taster experience for first time flyers that you like. You can always add time when you're there.
Most wind tunnels have viewing areas so you can watch the flyers in the chamber. Plan to arrive a couple of hours before your actual flight, this will give you time to watch other first timers and then you will gain a much better understanding of how it all works before you start to fly yourself.
It will be very noisy in and around the tunnel, so you probably won't be able to hear instructions clearly. Some may be given in sign language, think of it like a game of charades and you'll be fine. Don't get stressed out with the noise or the wind, or if a move doesn't come easily. The more you tense, the worse it will get, so instead take a deep breath, relax and force a smile. Ask about video and photos to take home. Enjoy the experience, because it will be over all too quickly!