Not really a characteristic, but if you are building your first plane, then cover it with a bright colour, not white. I found that white airplanes are fairly easy to lose orentation on a cloudy day, and that was the main reason that my instructor had to take over control. Sometimes I thought that the airplane was inverted.

As for the airfoil, thats a tough question. Semi symetrical will take longer to "outgrow", but I started on a LT 40, and the wing came off, so I bought a avistar. Flying was similar, but taking off and landing was slightly more difficult for me, especially without the flaps.