My glider was designed to have wings that provided a lot of lift, so we could successfully make it fly. However, we did have to make it be a little heavier in the back so we could provide enough drag so it would land properly. The surface area of our glider's wing had to be increased by using slats so we had two wings with even amounts of lift. Our airfoil also had to be shaved down on the wings so they wouldn't be too bulky and make gravity pull it down so much. We also designed it to where it would be easy for us to throw the glider and provide it with enough thrust to power it to go further.
We modified our glider by adding slats onto one of our wings. Our wings tested to be uneven in the wind tunnel, so we attached a notecard to the weaker one to try to even them out. We also ended up gluing our wings on differently, because they kept falling off when it would land. We glued it from the side instead of the bottom.
In order to throw our glider, you want to start by holding it in the middle of it with a firm grip. You then want to reach your arm back as far as you can, and aim for the middle or little bit upwards to your target. When you throw and release it, make sure you have plenty of power in your throw, and that you throw it accurately.