Start by setting some butter to melt - maybe a couple of tablespoonsful?.
You need bread: maybe two or three slices of fresh bread, whizzed in the blender.
A couple of rashers of bacon. Take off the rinds and chop or whizz the rest (I put the rinds on top of the bird, where they crisp while it cooks and often don't make it to the final plates of dinner...)
Parsley. I like a bit of this, maybe 1/3 of a bunch (four or five decently bushy stalks) - whizz in the blender, stalks and all (the flavour's in the stalks and the greenery adds green). Also nice when picked from your garden.
Put all the ingredients in a bowl and mix - the melted butter will bind them together. You want it just sort of holding together, not sloppy with butter.
Don't get fancy-schmancy with adding more herbs, or anything else (except maybe a little coarse-ground black pepper). Just try this once the simple way. You can make fancier stuffings/seasonings, but this one, simple as it is, is hard to beat. Fill the cavity of the chook, and roast it as you normally would (a chicken with stuffing always needs longer than a chicken without). Another family habit is to cover the chicken with bacon when you put it in to cook. Take the bacon off when it's nearly done so it can brown up nicely. See?