Stiff is good... You pull it tight so it presents a near flat surface to the blade.
You will not have to pull quite so tight with a thick sturdy leather. Recall that
some folk glue leather to wood to strop on.

With a supple strop the need to strop with no pressure is so very important. <------!!!!!!!!!
Practice stropping with a feather... or a tender roll of newsprint.....

Strop dressing... one trick is hand cream. After applying a small bit of
hand cream to your hands give the strop a rub. Lanolin rich hand creams
are nice for this.

Not directly on leather. A little on you hands well rubbed in then rub
the strop. If you pick up a water glass and it looks like a three year
old picked it up you are using too much goo.