I add several of the ingredients already mentioned here. I like to experiment with the flavoring(s), sometimes adding coffee, red wine, ginger, garlic, soy sauce, or worcestershire, or some sour cream (at the end) & variety of shrooms. A fave is serving it over broad egg noodles or in a (beef) pot pie with puff pastry. I have a beef-ginger stew recipe served in puff pastry. If anyone is interested, give me a wave.
All the above, skinned tomatoes, a bottle of stout for beef. I add mint for lamb tied up with rosemary and a bay leaf or three. I love pumpkin and Kumara (sweet pot) which melts in to the gravy and thickens as well as adding to the flavour.