RE: First flight Error?
Check the stall and snapping tendencies of the plane at altitude. Go up several mistakes high and throttle back slowly to idle while feeding in up elevator. Try and keep the plane flying as long as you can. Once it stalls, you'll see how it stalls and how slow you can go before it stalls.
You should find these things out on the first few flights of any model you fly for the first time.
Don't forget to balance the plane laterally too. Pick it up by the nose and tail and see if a wing is heavier than the other. Most planes need some counter weight on the light wing, and this will help with trimming the plane for straight and level flight and will reduce the tendency of the plane to roll into the heavy wing during a stall.
Jesse