I'm not saying it's the best way, it's just how I do it and it seems to work well. Velcro on the bottom of the GoPro, velcro on the part of the F450 frame that sticks out the front then wrap a length of velcro around the entire camera. The "shutter" button can still be easily operated through the velcro.
Simple, light and works. I used to use the protective case but what's the worst that could happen. If I write it off, I'd have to replace it with a new version 2 GoPro. Damn.