Piecing binding  was confusing to me, so I came up with a way to have perfect strips every time.

Take your strip right side down,  and fold  one corner in as shown

do the same with the second strip, only fold to opposite direction

line them up so that folds match

The pieces will end up perpendicular to each other as shown.

Sew along fold

Trim seam

Press open seam

Finished strip.

I hope you found this helpful!