The guide in my sig is for FAR, but most of it should still apply to Duna. The key thing is not necessarily to have big wings (although that does help) but to land on a flat place, and most importantly, kill a ton of speed before you land. On Duna, retrorockets may be a better way to do this. Check out the link in my sig for more info. --Edit-- Use that dropping out of the sky as an advantage, find a hill that slopes downwards not too steep and flare right before you land, the downwards slope had the effect of slowing down your vertical speed.