Well, as said!
I'm not too profficient in aircraft either, but I follow a very easy rule when designing/drawing my airplanes, something that APDAF could have use of as well:
Look a lot on IRL aircraft. When designing you own aircraft, take one or two planes from the 'bucket and start combining elements that you like from the,(no copy and paste though, try to draw said elements yourself in a plausible maner.), along with checking up the data of those planes. Just designing one out of the head without knowing a lot(I include myself among those who lack the knowledge)is really hard to get right.