Here's what I do for wall hangings.
after quilting and before adding binding
Measure width of WH. Example 20"wide. Divide in half = 10".
Cut two 10" squares and press diagonally in half.
Line the raw edges of each folded, pressed square on the upper corners of the back of the WH.
Baste the raw edges to the WH with 1/8" seam allowance.
Add your binding as usual.
Now you have two triangle pockets in the upper corners of the WH.
Measure a piece of sturdy cardboard as wide as the opening between the triangles and as deep or tall.
Slide the cardboard into the pockets, place the WH where you want to hang it and slide your hand into each pocket with a tack to push through the cardboard and into the wall. WH stays nice and flat and flush to the wall with no dowel bump.
Easy, peasy