Step 1: Step 1
fold it in half long wise to make a crease. un fold and then fold the top two corners into the middle.
fold this new triangle keeping the apex of it in-line with the middle.
Step 2: Step 2
now fold the little bottom triangle up.
fold the plane in half BUT make sure the little triangle you just folded up is on the OUTSIDE.
fold the wings about 2-3cm from the bottom.
tada! now it will fly fairly straight.