I now do a measurement on some peices before I glue them. To ensure I have the 1/2" LE vice the 3/8" TE. Ya only need to make that mistake twice before learning. I actually seperated the wing construction balsa part from the fuselage balsa parts. If I have too many balsa part in one area I easily get confused and trouble is soon brewing.

Oh! And one more thing! READ the directions! Dont just look them over, read them before starting. Then read them again as you are building.

Good Luck